The man is interested in prisoner 270-G. She dresses like a noble woman, yet she lacks the fear that every other ‘guest’ has shown from the minute they arrived. Leela knows this is an interrogation and regardless whether or not he gets the information he needs, one thing is clear - by the end of it, one of them will be dead. The man says he wants her to tell him about a lost world and he threatens to administer pain if she refuses. He demonstrates, and a sharp bolt of searing power burns through Leela’s body. She accuses him of being afraid to face her on even terms and challenges him to remove his armour, but he simply laughs. He says she’s a worthless female who’s only being kept alive for one reason - to provide him with information.

These were Leela’s final days. Her adopted home planet was gone and with it everything that stood between her and death. Since she’d been brought to this prison, her body had aged one year for every day. Thanks to the Doctor’s people she’d already lived longer than she thought possible, but now she was growing old. She recalled a place on the planet where she’d been born, a place where only the mightiest of warriors was allowed to go. It was called the Tro’faroom, a cavern in the depths of the forest where the ancient founders of the Sevateem had buried the remains of their first and most noble warrior. Ever since then, her people would take a symbol of every battle - an enemy skull, a weapon or a severed limb - and leave it at the cave. When her mother died, she went there to talk to the spirits of her ancestors, but she found nothing but a cave full of old bones. There was a metal sign there, like one of Neeva’s holy relics, and although it meant nothing to her at the time, she remembered the symbols. Years later, the Doctor taught her to write and she discovered the words said ‘Trophy Room’. The Doctor offered to show her his own trophy room some time, but first he said he was taking her to dinner as it was about time she learned some table manners.

The price Leela had to pay for travelling with the Doctor was that he wanted to ’educate’ her. One day, she found herself in an Edwardian house, sitting at the table of Lord Joshua Douglas, a straight backed man with an absurd moustache, and Lady Douglas, a straight backed woman with a nose like a hawk. Their tiresome daughter Jessica giggled every time Leela spoke and it was lucky she didn’t stab her with a Janis thorn. A strange old man called Williams served their food and he frowned whenever she carved the meat or wiped her hands on the tablecloth. Eventually Leela told Jessica how annoying she was - and Lady Douglas gasped, although her husband simply laughed. Lady Douglas asked Williams to take Leela down to the servants’ hall as she felt it would be more appropriate for her to dine there. Leela agreed to go, but said that if the meat down there was as old as the meat here, she’d go hunting for her own supper. As she left the room, she glimpsed the Doctor telling Lord Douglas they needed to talk…

The house smelt of decay and dust. As Williams led Leela down a narrow corridor lined with dying plants in pots, she froze as she heard a distant sound inside her head, like a voice calling for help. Jessica emerged from the dining room and told Leela she‘d been asked to show her the house and gardens. It seemed her father thought they could both learn something from each other, but they both agreed it wasn‘t a good idea. Jessica explained that ever since her father had returned from his trip, his views had become somewhat eccentric and her mother blamed the Doctor and his friends. Leela learned that Lord Douglas had previously travelled with another man called the Doctor, although he was a much older man than the one here today. He was only gone for a year, but the journey changed Jessica’s father dramatically and when he returned he looked ten years older. Some of the servants believed they hadn’t really gone to Peru at all, but that the Doctor had ’bewitched’ Lord Douglas.

Leela asked what was downstairs and Jessica said it was just the servants’ hall and the cellars. Leela told her something was trapped down there as she’d felt its pain. Ignoring Jessica’s protests, she went to the servants’ hall and opened a door leading to a long dark corridor. The walls were damp and the air was cold, but Leela was sure this was where the cry had come from. Jessica said this room was out of bounds to everyone in the house. Behind a curtain at the end of the corridor was another door and Jessica said the servants told stories of a maid who went in there one day and never came out again. The maid was said to have locked herself in, but at night she could be heard clawing against the door. Leela dismissed the story as nonsense, but then she heard the cry again. Jessica couldn’t hear anything, so Leela returned to the kitchen and found a large axe, which she then used to break the door down.

The room inside was pitch black and was even colder than the corridor. There was a rancid smell which Jessica identified as mothballs. The young girl switched on a light and was amazed to see it was coming from long glowing tubes on the ceiling, the like of which she’d never seen before. It was a small room filled with assorted objects, including a shining metal cup which had an inscription on it stating that Jessica’s father had won first prize in a race - in 1953.

Among the other objects was a picture of Lord Douglas next to an old man with white hair standing in front of futuristic buildings that looked nothing like the ones Jessica had seen of Peru. To Leela, the answer was obvious - the Doctor must have taken Jessica’s father to another world and this room was where he kept his trophies. Leela started searching the room for whoever cried for help, even though it seemed impossible for anyone to be trapped in here as there were no hidden doors or panels. Jessica wondered whether Leela was a suffragette. Her mother had called them “abominations of nature” and said they should “know their place”, but this led to her having a terrible argument with her father, as he supported their movement.

Jessica noticed a hole in the floor through which a green light could be seen. Leela used her knife to remove the floorboard and underneath they found three shining green buttons. Leela pressed them and the entire stone cellar disappeared around them, to be replaced by a warm room with walls lined with books. Jessica was speechless at the metal objects, maps and drawings of other worlds that filled the room. There were also weapons of all different sorts and at the centre of the room on a raised platform was a suit of armour big enough to contain a large man. The suit had a tail and the helmet was shaped more like an animal’s head than a man’s.

Jessica pressed a switch on the wall and the creature inside the suit of armour began to move. Jessica screamed and Leela quickly picked up the nearest weapon to defend them, but then the creature assured her he meant no harm and that he was contained within a force field. The creature said he’d ‘felt’ Leela’s presence upstairs and had called out to her. His name was H’mbrackle and he was an officer of the Z’nai, a noble race of warriors dedicated to maintaining order throughout the system. He was the last of its race and the others had been wiped out by their enemies, but he’d been condemned to a life of solitude and imprisonment. He asked Leela to release him, but she knew he must have been put here for a reason. The warrior asked Jessica if she trusted him, then realising his appearance must be daunting, he removed his helmet to reveal a beautiful face with a long mane of golden hair.

Leela knew Jessica had never seen an alien before, but the Doctor had taught her never to judge by appearances. H’mbrackle recognised the Doctor’s name and knew him as a man of learning, but also of many contradictions. He said he and the Doctor had dined together at the Royal Palace of Kremnon on the day the walls fell and they spoke of literature, art and poetry. H’mbrackle’s father was a particular favourite of the Doctor’s. He said not all his race were warriors and the Z’nai also boasted some of the finest philosophers in the Universe - their architects had created some of the most fantastic hanging fountains and sky cities. Leela asked why his race was destroyed but he suggested she should ask the Doctor. Then he warned that the Doctor didn‘t always act in the name of peace and said in some ways the Doctor’s mind was as closed as those he professes to protect.

When he indicated that Leela might not understand his words because she’d never killed, Leela said he had killed to protect herself and even in sport. She admitted it wasn’t always done with the Doctor’s blessing, but H’mbrackle mocked the Doctor’s moral outrage. He said the Doctor once gave a speech to their Emperor, urging him to mend his ways and stop the meaningless slaughter of billions, but H’mbrackle argued their actions were fully justified and every one of those deaths was honourable and noble. He also pointed out that the Doctor was himself an authority on killing and was steeped in blood. Then, to Leela’s shock, he revealed that it was the Doctor who destroyed his race. H’mbrackle said he watched his people die one by one, including his wife and young child, and he felt as though he shared some of the blame because he’d dined with the Doctor earlier. Then, when the Doctor condemned him to a living death in this prison, all he could see were the faces of those he’d loved dying in agony at the Doctor’s hand.

H’mbrackle said he could have prevented the genocide, but instead he spared the Doctor’s life because he believed his lies about the greater good. On hearing these words, Jessica declared that H’mbrackle must be telling the truth and that the Doctor was indeed responsible. She said her father had written a story called “The Greater Good” about a long lost tribe he encountered in Peru. In the book, the tribe were savages who slaughtered everyone who trespassed on their land. Her father and his friend had a choice - they could either destroy the tribe or they let them steal their ship and put the British Empire at risk. They chose to destroy the tribe for the greater good.

H’mbrackle assured Leela he had no desire for vengeance and said his father’s poetry spoke of tolerance and forgiveness. He said he’d be content if he could live what remained of his life in peace. He asked Leela to release him, but she refused and said she’d speak to the Doctor. Jessica insisted on staying behind as there was a lot she could learn from speaking to H’mbrackle, so Leela warned her to be careful and told her not to touch anything in case the creature was lying.

Leela used the controls to return to the stone cellar, but she found herself facing an angry Doctor, who stared at her silently. Leela recognised his dark mood and knew she shouldn’t cross him while he was like this, but she needed some answers to her questions about the creature and about the Doctor’s past. He noticed she still held an alien weapon in her hand and asked her to hand it over, then he revealed that it was actually a food blender given to him by the head chef at the Raffles Hotel in Singapore after he helped him fix a light bulb. When he saw the framed photograph of Lord Douglas, his face darkened again. He confirmed to Leela that he’d travelled with Jessica’s father for quite some time, but he was vague when she asked if they’d ever been to Peru. She asked why they stopped travelling together and the Doctor said he’d had a difficult choice to make and Lord Douglas had disagreed with his decision.

Leela prompted the Doctor and said he must have made the decision for the greater good, but this worried the Doctor and he suddenly realised Jessica was missing. He was horrified when Leela revealed that she’d left the girl alone in the trophy room. The Doctor pushed past her and pressed the controls in the floor - and they were both transported into the other room. The room had been ransacked. The Z’nai prisoner had gone and a gaping hole in the wall revealed a long stone corridor, at the end of which were steps leading to a wooden door. Leela briefed the Doctor on everything H’mbrackle had told her and she demanded to know if it was true he killed the entire Z’nai race. He completely denied everything and then laughed at the idea that H’mbrackle wanted to live the rest of his life in peace.

The man checks in on prisoner 270-G and finds that she’s still alive, but is still unwilling to talk. Leela insists that he address her by her name, but warns that she won’t tell him anything. The man is confident she will - it might take days or weeks, they might have to starve her or even torture a friend in front of her - but she’ll talk eventually. The Z’nai fires another bolt of searing power through her body, then he asks her again about the lost world.

Jessica Douglas’s neck had been snapped. Leela knew they’d need more than her knife to kill the creature, but the Doctor insisted they weren’t going to kill H’mbrackle. As he entered the other room, Leela went back for a large spear, but when she opened the door at the top of the steps she found herself facing a brick wall. Furious, she returned to the trophy room and used the controls to send herself back to the house. As she appeared, she heard a terrible scream and knew immediately that the creature had killed Lady Douglas. Passing the dead bodies of the servant girls and Williams, she raced towards the room where the TARDIS had landed.

She found Lady Douglas’s corpse and then, through the door, she saw Lord Douglas being held up in the air by his neck. The Doctor was begging H’mbrackle to let him go, but the warrior refused and said the old man was of no value to him or his army. As he killed the man, the Doctor turned on him angrily and demanded an end to all the senseless death. H’mbrackle said the Universe had been infected with human beings for too many years and his race were purifying the system and ridding it of deviants and lesser beings. The Doctor asked what gave him the right to decide who lives or dies, but H’mbrackle pointed out that it was he who decided the Z’nai weren’t worthy enough to live. The Doctor said he gave them a choice and they could have closed the purification camps any time they wanted. H’mbrackle accused him of being self-righteous and said he gave the Doctor a choice too - he could have sat at his side and used his position of power to make sure the Z’nai upheld everything he held dear. The Doctor said the offer was only made if he’d agreed to become like them, cloned and stripped of all his individuality.

The two men faced each other, both waiting for the other to make the first move, then H’mbrackle went to grab the Doctor. Leela threw the spear at the creature, but he caught it easily and snapped it in two. He knocked her to the ground, then complimented her on her courage. Then, H’mbrackle’s entire body started to shudder as if he was in pain. He turned to the Doctor in confusion and said he’d promised him he would be immune…then he staggered backwards. He begged the Doctor to spare him, but Leela mocked him and told him to join the rest of his people in Hell.

H’mbrackle fell to the floor. The Doctor and Leela hauled his body into the TARDIS and into a room Leela had never seen before. The Doctor pressed three green buttons and suddenly they were transported back to the steps outside the trophy room. Leela couldn’t work out whether this place was actually in Lord Douglas’s house or whether it was part of the TARDIS, but the Doctor says it was neither and was just in-between. They returned H’mbrackle to the platform, then the Doctor spread a thick green liquid on the warrior’s armour. H’mbrackle woke up and his strength returned, but then the Doctor flicked a switch and he was imprisoned again. The Doctor explained that he’d cured the warrior and said that if he’d let him die, he’d have been no better than the Z’nai.

He then revealed that it was Lord Douglas who originally released the virus that killed the Z’nai and made the decision for the ’greater good’. Leela said it was the right decision, but the Doctor disagreed. He said the Z’nai were once a noble, peace-loving race and H’mbrackle’s father was an inspiring leader who wanted his race to live in harmony with everyone else. It was only H’mbrackle who thought those views were unacceptable. He bullied and brainwashed his people into unspeakable crimes and although the Doctor tried to appeal to the compassion they once had, he failed. When the virus was released, the Doctor tried to find an antidote, but H’mbrackle had made them so distrustful of others they were too afraid to let him. The Doctor said this wasn’t a prison, it was a quarantine cell. H’mbrackle was the carrier and by putting him here, the Doctor hoped to save the rest of the Z’nai. He’d come here today to cure him so he could return to his people and lead them into a new enlightened age, but Lord Douglas thought he was wrong and wanted to kill H’mbrackle. The warrior laughed and said his people would eventually rescue him. By saving his life, the Doctor had signed the death warrants of all lesser species.

The Doctor flicked another switch, freezing H’mbrackle in his cell forever. Leela argued this was no better than killing him, but the Doctor said while there was life, there was always hope. The Doctor was still baffled as to why H’mbrackle developed the disease just now as until today he’d just been a carrier. Suddenly they heard the sound of the TARDIS’s Cloister Bell and moved outside. They saw a huge spaceship coming in to land outside the house and the Doctor identified it as a Z’nai Angel of War. The windows of the house were smashed as a hot torrent of air crossed the street and then there was complete silence. Leela suggested returning to the TARDIS, but the Doctor had been knocked unconscious by a falling beam. She saw a doorway open in the Z’nai spaceship and then a group of soldiers emerged and headed towards the house…

Leela tried to drag the Doctor away, but the Z’nai opened fire and she had to take cover. There were about 30 warriors standing in a line with their guns pointed at the house. One of them entered the building and questioned Leela, but she told him she didn’t come from this world or from this time. The soldiers moved away from the spaceship which then seemed to darkened until it finally exploded into dust. The Z’nai warrior told Leela they’d anticipated the temporal destruction of their ship as it was only able to make one journey through time. He removed his helmet and she was shocked to see that he looked and sounded exactly like H’mbrackle. The officer told her he was reborn in his Emperor’s image and ordered her to take him to his leader, saying they planned to conquer this world and use it as their new centre of power.

The warrior dug his fingers into Leela’s cheeks and demanded she give him the information he needed. Then suddenly his skin started to change, just as H’mbrackle’s had done earlier, and he rapidly blistered and aged. Another soldier ordered the first warrior to be eliminated immediately and he was instantly shot down. The new officer, who also looked and sounded like their Emperor, ordered Leela to be restrained while they searched the building. Leela was left with a guard and she asked him why the Z’nai needed their Emperor if they were all the same as him. The guard, whose name was K’mbarthy, said H’mbrackle was their inspiration and that he would lead them into their final battle. The guard said he was once an architect, but that life had gone now and he would willingly kill or die at the behest of his Emperor. Leela asked him why he regarded humans as their enemies as they weren’t even aware of their existence, but he said they must be eradicated because they were different. K’mbarthy revealed that in the future, in the vast war of the third generation of Kremnon, humans and Z’nai will fight alongside each other, but H’mbrackle had told them the humans would eventually betray them and spread across the system like a disease.

As Leela continued her questioning, she saw the Doctor’s eyes open. K’mbarthy told her his family were killed by the same disease that wiped out the rest of the Z’nai, but he said it happened earlier, during the time before the purification. He said some people thought the disease was created in the Palace laboratory and that the Emperor himself had condoned its creation, but he didn’t believe that. Leela said she’d heard that their legends blamed the Doctor, but K’mbarthy said many people spoke about the Doctor before the Great Death and a few even dared to say he was their only hope for a better future…but anyone who believed that now was thrown into the purification camps along with all the other vermin.

Suddenly the Doctor leapt to his feet and knocked K’mbarthy to the floor. Leela tried to disable him by thumping him in the chest, but this caused his skin to blister and foam. The Doctor and Leela examined the bodies of the two dead Z’nai, unsure what had happened. The Doctor realised that for some reason Leela had herself become a carrier, a catalyst like H’mbrackle once was. Before they could react, the other Z’nai soldiers returned and the newly self-appointed leader demanded to know what had happened to K’mbarthy. The Doctor introduced himself and as the warrior raised his weapon, Leela grabbed his hair. Once again, the effect of the disease was immediate and blisters began appearing on his face. Another warrior entered and Leela lashed out at him too. When a third warrior entered, the Doctor called to Leela to stop what she was doing. Distracted, Leela was nearly knocked out by the latest arrival, but when he turned to open fire on the Doctor, she spat in his face. Within minutes, all three Z’nai soldiers were dead and a foul smelling steam rose from the corpses.

The Doctor was appalled, but was stopped by the arrival of a fourth warrior who demanded to know where they’d imprisoned H’mbrackle. The Doctor surrendered and offered to show himm, but already the remaining soldiers were all starting to succumb to the effects of the disease. The virus had become airborne. The Doctor urged the Z’nai to leave the area, but it was too late and one by one they all fell to the floor and died. The Doctor and Leela stood in silence, shocked by what they’d seen.

An hour later, the Doctor emerged from the cellar and drenched the curtains and carpets of every room with petrol. He told Leela that he’d failed his friends and his people and he’d even failed the future. Leela asked him what he’d done to H’mbrackle, but all he’d say was that nobody would ever find him. The Z’nai Empire lay at the Universe’s darkest hour and he couldn’t allow any of this to happen again. He told Leela they’d never come back here, then he lit a match and set fire to the entire house. They entered the TARDIS and disappeared…

The interrogator mocks prisoner 270-G. She’s so old and so close to death, yet she still has strength to equal any of the Z’nai soldiers. Weakly, Leela asks the man what his name was before the purification and he’s surprised to learn that she already knows something of their ancient history. She knows the man didn’t always have the face of H’mbrackle, but she also knows his ancestors were braver than he is. He says she’s referring to a time centuries ago when the Z’nai race was scattered across the Universe. He removes his helmet and says he likes to look his enemies in the eye before he kills them. Leela offers him a choice - if he agrees to stop the killing and close the purification camps, she’ll spare his life. The man laughs…