Here are the headlines at midday. The world’s first space flight for tourists could be ready for lift-off in a matter of months. The maiden voyage of the Dauntless hadn’t been expected until 2008, but today it was announced the revolutionary spacecraft could take to the sky by Christmas. Officials at NASA have expressed concern that the Dauntless project team is cutting corners to beat its competitors into space, but pilot Ben Kimmel has dismissed those fears: “NASA’s trying to frighten investors away from the Dauntless to protect its government funded monopoly on space. They know if we succeed NASA will be as dead as a dodo within twenty years”.

Britain’s leading forensic archaeologist Dr Gareth Edmons has left for Florence to take charge of the Medici Project. He’ll lead a team exhuming Tuscany’s most famous family from underground crypts that date back nearly 500 years. Dr Edmons discussed the project before his departure: “This is one the most exciting digs I’ve ever been involved with. The Medici Project has already found evidence that challenges the previously accepted history of Renaissance Italy. Who knows what else we’ll find beneath San Lorenzo? I only wish I was joining the project under happier circumstances.” Dr Edmons’ predecessor, Professor Gian-Carlo Brunetti, vanished without trace a month ago. Italian police admit they’re baffled by his disappearance.

Here, police are investigating the sudden death of Hilda Winters. She was under house arrest awaiting trial for the theft of sarin nerve gas pellets two years ago. A spokesman for the Metropolitan Police said Miss Winters’ death was not suspicious and nobody else was involved. Her co-accused, Philip Harris, was shot dead last month while trying to escape.

Sarah answers the phone, but is angered to find it’s another journalist who’s tracked down her ex-directory number. She has no intention of making a statement and hangs up. Josh arrives at the cottage and they greet each other warmly. She apologises for asking him to house-sit at such short notice, but she’s been door-stepped by tabloid hacks twice already today and caught another one going through her rubbish bins. She’d received a call from DI Morrison earlier to tell her about Miss Winters’ death, but she’s not sure how she feels as she doesn’t wish death on anyone. She wants to change the subject and Josh admits that he’s quit yet another job - that’s seven in two years! The problem is that nothing he’s qualified for compares to the adventures they had. Sarah tells him she’s been busy sorting out Aunt Lavinia’s inheritance and is helping to fund other people’s good causes. The taxi arrives to collect her and Josh starts fishing for information about where she’s going, but all she’ll tell him is that she’s hoping to see an old friend tonight.

At the Medici Project in Florence, Nat shows Dr Edmons into the mortuary where the burial boxes are to be opened. He’s very impressed by the scale of the operation and learns that they’ve exhumed twenty coffins so far, but the Basilica di San Lorenzo is open during the day so they work mostly at night. Unfortunately everything was put on hold after Professor Brunetti disappeared. He’d been searching for concealed chambers in the crypt, but Brunetti’s assistant Luca Parenti will have to show him where as Nat can’t get down there in her wheelchair. Luca and Edmonds go down the ladder to the lower level while Nat takes a phone call. It’s Josh again, claiming that he’s worried about Sarah because she’s been acting strangely. Nat recalls that Sarah always used to mark some sort of anniversary on this date so Josh goes through Sarah’s diary and discovers she’s due to meet someone called Harry at eight o’clock in a restaurant not far from Blackfriars in London. Josh is interrupted by someone at the door with a recorded delivery letter. He thinks it looks important, so taking it to Sarah will be a good excuse to see what really she’s up to. Nat warns him not to do anything silly…

A slightly tearful Sarah arrives at the restaurant and recalls that it’s been a year since she last came here. She remembers her days with UNIT, with everyone risking their lives to save the world from threats that nobody else even knew existed. Some days it feels like only yesterday, but other days it seems like a lifetime ago. She knows she can never discuss it with Nat or Josh and she’s starting to wonder whether she imagined the whole thing. She drinks a toast to Harry, wherever he is. Just at that moment, she’s approached by a man who asks if he can join her. He introduces himself as Will Sullivan, Harry’s younger step-brother. She doesn’t recall Harry ever mentioning having a brother, but this doesn’t surprise Will as he never liked to discuss his family. Will explains that when he was growing up, Harry often used to come round for Christmas and birthdays and he seemed more like an uncle than an older brother. He’d already joined up by the time Will was a teenager and it was his stories about being a naval doctor that encouraged Will to study medicine too. When Harry left the Navy and joined a top secret intelligence taskforce, his stories became wilder, more like science-fiction, yet he made it all sound so real. He claims that Harry often used to mention Sarah. He’s staying at Harry’s flat at the moment, which is how he knew about their appointment. He gets out a photo of her and Harry that was taken at the hotel near Loch Ness.

Nat sets up a video camera and starts recording as Dr Edmons introduces his assistant, Luca, and explains that he’s about to open the twenty-first casket the archaeological team have uncovered in the underground crypt below the Church of San Lorenzo. According to their records, the small coffin should contain the body of Phillipino Medici, the young son of Grand Duke Francesco I. There is evidence of water damage from the flood of 1966, but the seal remains intact, which suggests the box has not been opened for 400 years. Dr Edmons opens the seal and the group is suddenly hit by the terrible stench of decomposition. This doesn’t make any sense as the body should have mummified centuries ago. They remove the lid and are horrified to discover a fresh corpse inside, dressed in modern day clothes and with his arms and legs broken to fit inside the small coffin. Luca recognises the half-decomposed face - it’s Professor Brunetti, the project’s missing chief archaeologist! Nat turns off the camera as Dr Edmonds orders her to call the police.

Will tells Sarah he’s just spent the summer in Antarctica as base physician for a British research team, which reminds her of her own experiences on the ice. He explains that he came to the restaurant in the hope of bumping into Harry, who’s been missing for some time on a hush-hush mission. He’s been gone so long now that Will has almost given up any hope of finding out what’s happened to him. Unfortunately Sarah can’t help him as she hasn’t met Harry since he left for his overseas posting. He couldn’t tell her where he was going or when he’d be back. She still keeps her regular annual appointment, just on the off chance that he’ll turn up. She suddenly realises she’s been talking about him in the past tense, as though she knew he was dead. She starts to cry…

Josh arrives at the restaurant and sees Sarah having a drink with a man dressed like an ex-public schoolboy, who he takes an instant dislike to. He assumes Sarah is on a date, but he gets angry when he notices she’s crying. Sarah pulls herself together and apologises to Will, but he’s sympathetic and offers her a lift to the station. As they get up to leave, Sarah spots Josh and storms over to him, demanding to know why he followed her! He makes a weak attempt to explain his presence by handing over the letter, but she’s not fooled for a moment. Will joins them and Josh rebukes him for making her cry. Sarah is annoyed by Josh’s over-protective nature and the fact that he’s mocking Will’s posh accent. She promises to have words with him tomorrow, then she leaves with Will.

Luca reports back to Dr Edmons and tells him the police have ordered everyone to stay at the crypt until they arrive. The elderly archaeologist can’t understand why anybody would want to hurt Professor Brunetti as he seemed such a nice man. Nat confirms that it was definitely murder as she’s noticed a bullet wound on the dead man’s temple. The other mystery is how the killer could have placed the body inside the casket without breaking the seal but she discovers the bottom of the box had been broken open and then hastily repaired afterwards, so that it wasn‘t visible from the top. She suspects thieves had probably thought the coffin might contain jewels, but Edmonds points out that thieves would be unlikely to go to such lengths to hide the body.

As Will drives Sarah to the station, she apologises for Josh’s behaviour. He may be a rough diamond, but he obviously cares for her. She asks him about his work in Antarctica as she has herself donated some of her inheritance into an ecological study there. Will is familiar with most of the bases on the continent and asks her which one she’s funding. When she reveals that it’s a project to drill for ice-core samples to calculate when global warming will reach tipping point, he realises she’s talking about the Nikita Base under the leadership of Gideon Munro. Incredibly, this is the very team he’s working for! He’s leaving for there tomorrow and will spend the next thirteen months at the Base. They arrive at the station and he realises that because she’s funding the research it shouldn’t be too difficult for him to arrange for her and Josh to visit. He leaves her his card with his email address and asks her to keep in touch.

It’s almost dawn in Florence and Nat, Luca and Edmons are exhausted after being questioned for hours by the police. The murder will be an embarrassment to the city and the authorities will be pressing the police for an early arrest. Nat’s phone rings - it’s Josh again. She tells him about the death of Professor Brunetti and the fact that everyone who works for the Medici Project is a suspect, including her! Edmons hasn’t slept for 24 hours so he heads back to the hotel, while Luca escorts Nat home. He’s frustrated that the crypt will now be crawling with police looking for evidence which is ironic as his team contains some of the world’s best forensic specialists and none of them will be allowed to help. Nat is curious to know who chose which of the coffins to exhume first. Luca tells her the decision was Dr Edmons. She realises there are still over a dozen caskets left, so it could have been months or even years before the body was found.

Josh arrives at Sarah’s cottage the next morning, looking rather shamefaced. He feels even worse when she lets him in and he sees she was burgled last night and the entire house was completely ransacked. There had been a spate of break-ins in the area recently, which is why she asked him to house-sit. She knows he meant well, but she thinks it’s time he let her look after herself. Fortunately nothing appears to have been stolen. As they tidy things up, Josh tells her about the murder in Florence and Nat’s interrogation by the police. Sarah wants to fly straight to Italy, whether Nat likes it or not. Josh remembers Sarah’s letter and when she opens it she finds it’s from Miss Winters, written just before she died.

The Keeper, a woman with a deep sultry voice, receives a phone call from one of her acolytes telling her that they searched Sarah’s house thoroughly but found no sign of the letter. She decides not to have him take the letter by force as this would only draw attention to it. Instead, she will rely on Sarah dismissing its contents as the last spiteful act of an old adversary. Before he returns to the Chapterhouse, the acolyte tells her he left listening devices in Sarah’s cottage and overheard her planning to visit Italy. The Keeper will need to warn their contact in Florence.

Sarah is shocked by Miss Winters’ letter and needs to get some air, so Josh joins her in the garden. The letter, some of which is in Latin, contains a mix of threats and wild accusations, but Sarah is intrigued by a warning that she’s being watched by people close to her. Miss Winters explains that Sarah’s life is of more significance than either of them realised and she should beware the scarlet acolytes of something called the Orphans of the Future. There’s also a note stating that the Book of Tomorrows is opening. Convinced that Nat can help them, Sarah is even more determined to go to Florence.

Here are the headlines at midday. The British millionaire and philanthropist Sir Donald Wakefield has confirmed he will be a passenger on the first space tourist flight scheduled to take off from Nevada later this year. Sir Donald is battling cancer, but says he will be well enough to take the historic voyage on board the privately funded spaceship known as the Dauntless. He joked with reporters about the flight at a news conference in London today: “I want to see the heavens before I move there permanently, you understand. I never acquire a new residence sight unseen.”

Animal rights activists have stepped up their campaign against the staff at the Pangbourne Research Centre in Reading, near Berkshire. Last night there was a firebomb attack on the home of Dr Gavin Dexter, Head of Research at the laboratory. Police say nobody was hurt in the incident but Dr Dexter’s property suffered significant damage. We spoke to Maude Fletcher, veteran campaigner, who‘s maintained a round-the-clock vigil outside the facility in Pangbourne since last Christmas: “I certainly don’t approve of, nor condone, attacks on private property. The vast majority of animal rights activists are peaceful people who simply want an end to needless and cruel experimentation. Nearly three million animals were used and abused on the name of medical science last year. How would you feel if it was happening to your children?”

The remains of missing archaeologist Gian-Carlo Brunetti have been formally identified in Florence. Ironically his body was unearthed by the Professor’s replacement, British forensic expert Gareth Edmons: “We’re still coming to terms with this loss. I’ve been asked not to disclose the details of what we’ve found but I can say this, Professor Brunetti’s death is a sad blow. Our sympathies are with his wife Isabella and their three children.”

Nat collects Sarah and Josh on their arrival in Italy. Sarah comments on how contented she looks, despite everything that’s happened, and she wonders when they’ll get to meet her mystery boyfriend. In fact, Luca is waiting for them at the hotel with Dr Edmons. Nat has already had a chance to do some preliminary research on Sarah’s letter - the Book of Tomorrows is considered in certain circles to be one of the most significant texts ever written. Back in the 16th century an Italian scholar started writing a journal which became known as the Book of Tomorrows. Its pages were made from two kinds of paper, one black with white lettering and one white with red lettering. It contains several predictions, and not just vague prophecies open to interpretation, they were apparently very specific and made mention of an apocalyptic event due in our lifetime. Parts of the journal were lost over the centuries and the book disappeared completely about 100 years ago, reportedly stolen by a sect obsessed with the end of the world.

The sect was made up of scientists, philosophers, inventors and other key figures across Europe and North America who held enormous influence and called themselves the Orphans of the Future. They believed man’s development had been aided by alien intervention and each visitation was preceded by the emergence of a human herald. The Book of Tomorrows predicted that the alien intelligence would return for a final visit before the end of the last Millennium. Over the years, two different interpretations of the text emerged. One half of the sect, called the White Chapter, believed the aliens would take them away to a better life, while the Crimson Chapter believed the aliens were coming to wipe us all out. Obviously the last Millennium has now ended and the final visitation never happened, so the two sects presumably fell apart as no one has heard of them since - until Miss Winters wrote to Sarah, claiming her activities were funded by the White Chapter.

Dr Edmons receives a call from the police telling him they’ve finished their work at the crypt and the Medici Project will be able to start working again later tonight. Nat brings over Sarah and Josh to introduce them and Edmons seems to recall Sarah from her previous television appearances. Luca offers to give them a tour of the crypt after they‘ve settled into their hotel, but Edmons appears a little flustered and makes his excuses, leaving Luca to go to the crypt first to see what condition it’s been left in. Thinking he’s alone, Edmons makes an urgent telephone call to someone with a warning that the person they’ve been expecting has arrived. He says he recognised her from her initials and the description given in the Book of Tomorrows - the prophecy is coming true at last! Suddenly the phone goes dead and Dr Edmons is shot dead.

Later that evening, Nat brings Sarah and Josh down into the crypt beneath the Basilica di San Lorenzo, the final resting place of the Medici family. She’s surprised that neither Dr Edmons or Luca are waiting for them, but the underground sections are huge and she can’t get access to them herself. Nat explains that Professor Brunetti was looking for secret rooms when he disappeared. Two years earlier he’d discovered a chamber with eight previously undiscovered caskets inside and he felt there must still be other hidden spaces. Nat stays behind while Sarah and Josh climb down a ladder and move further into the catacombs.

Nat tries to find Luca and Dr Edmons, but there’s no response. She hears a noise nearby and realises she’s not alone… As Sarah and Josh explore the beautifully carved tunnels, they wonder why anyone would want to murder a forensic archaeologist. Maybe during the dig he found something that wasn’t mean to be found? Suddenly the low-level lighting in the tunnels start to fade and they’re left in complete darkness, except for a faint glimmer of light ahead of them. They hear Nat calling out, but then she goes quiet. Josh goes back to see if she’s alright while Sarah continues her exploration… Josh goes back up to the main crypt and finds Nat unconscious!

Sarah hears Josh calling out to her urgently. He tells her somebody attacked Nat but he thinks she’s going to be OK. Then everything goes quiet. Sarah finds a small concealed room that she thinks might have something to do with Professor Brunetti’s murder. The faint light is coming from a torch inside and she would never have found it if the main lights hadn’t failed. Further in, she discovers the walls are lined with hundreds of pages torn from a book - and some of those pages are black with white writing! They would appear to be from the Book of Tomorrows, yet they’re written in English. Suddenly the door to the room closes behind her…and Luca emerges from the shadows. He holds her at gunpoint and claims that her discovery of the room was destined. He confesses to murdering Brunetti and hiding his body in the hope that it wouldn’t be discovered for years. Both Brunetti and Edmons were “false disciples” who’d come there looking for the missing pages from the book which reveal the herald’s identity. But Luca has already found the truth…

He asks Sarah to shine her torch at some of the pages on the wall. She reads the prophecies about how the aliens brought not only destruction, but enlightenment too. A woman is said to have arrived at the same time, carrying wisdom from the future. Her name was Sarah! At first Sarah believes this is nothing more than a coincidence, but Luca explains that earlier pages from the book referred to the herald by the initials SJS. The prophecies state that her arrival here would be the final portent. His aim now is to ensure that his enemies in the White Chapter never learn of her identity as they might still have time to stop what his Brethren are planning. He plans to kill her now and leave her body hidden in the secret room where it will never be found. Sarah continues to insist that she has nothing to do with this - but then she switches off the torch, plunging the room into darkness. He starts firing into the shadows and she is injured, but just then Josh returns and struggles with Luca. Sarah hears more shots being fired…before she finally passes out.

Here are the headlines at one o’clock. Two forensic archaeologists were shot dead yesterday in a bizarre incident at the Medici Project in Florence. The bodies of British doctor Gareth Edmons and his assistant Luca Parenti were discovered in the crypt beneath the Church of San Lorenzo by tourists. Local police are still investigating the case but believe an academic argument may have turned violent. A British woman caught up in the incident is recovering from gunshot wounds in a Florence hospital. Her name’s not yet been released, but her condition is said to be stable. The shooting happened less than 24 hours after the corpse of another academic, Professor Gian-Carlo Brunetti, was found hidden inside a 400 year old coffin.

Sarah slowly recovers in hospital and receives a visit from Josh. She’s lost a lot of blood and it was touch and go for a few days. Nat was only knocked out and is waiting outside, but she’s not taken the news that Luca was the murderer very well. Josh was also shot in the arm, but wasn’t seriously hurt. Luca must have thought he was dead so Josh was able to follow him down into the concealed room without his knowledge. The police want to talk to Sarah, but she doesn’t know how much she can tell them as she still has more questions than answers. Sarah asks what happened to Luca and Josh reveals that he had no choice but to kill him. This is now the second time Josh has killed someone to save her life and although she doesn’t approve of killing, she’s pleased that he’s always been there to protect her.

Josh leaves and Nat comes in to visit Sarah. She appears quite bitter about what happened and believes Luca was only with her to get to Sarah, but her friend explains that he was already dating her before he even knew of Sarah’s existence. Nat has decided to go away for a while and she asks that no one try to find her. She wants to be on her own for a bit and says goodbye. Sarah is devastated.