At the morgue, the old man’s autopsy proceeds with no surprises... until Johnson arrives with the identification papers. The dead man is apparently Toby Davenport, who is only 18 years old.

Life in Cloots Coombe is returning to normal, or as normal as it can get. Ellie Martin has moved back to the city for a while, and she’s holding a spot on the street for the missing Toby Davenport. Josh runs into her, and passes the story of Toby’s disappearance on to Sarah. She takes an interest for the missing boy’s sake, particularly when she learns that the police are being surprisingly tight-lipped about it. Natalie does some digging for Sarah, and learns about the “misidentification” of the corpse, which has thrown the whole concept of fingerprint identification into doubt. The investigation has been blocked by the highest levels of the government, but Sarah is an old friend of Claudia Coster, an administrator in the Ministry of Intelligence. Through Claudia, Sarah learns that the incident is somehow linked to millionaire philanthropist Will Butley, without whose contributions the Prime Minister would have had serious trouble financing his last campaign. Butley lives in a manor on the Yorkshire Dales, and Josh thus finds himself accompanying Sarah out to the countryside once again...

In his home on Haltooth Hall, Butley throws a temper tantrum, throwing his lunch to the floor and demanding his daily draught. His caregivers, Nurse Jephson and Ron Sharpe, have had to go through this before, and Sharpe is thoroughly sick of it -- and of Butley. Despite what they once had together, Sharpe is revolted by Butley’s senile pawing at him; but he still needs Butley alive for now, and he thus tolerates Butley’s bouts of dementia and abuse, as revolting as he finds the old man. Soon, however, he will reach his limit.

Josh and Sarah track down Holtooth Hall, and are surprised to find that it’s now the Huang Ti Clinic. Sarah and Josh try to bluff their way past the gate guard, Read, but fail. As they leave, Sarah remembers having heard the name of the Huang Ti Clinic before; pop star Lotus, an apparently ageless beauty, quickly left the public eye after she was expelled from the clinic for her behaviour, and she soon became far less beautiful. Through Natalie, Sarah learns that the clinic was named for the founder of Taoism -- a philosophy which, like alchemy, involves the pursuit of spiritual and physical immortality. Nat directs Sarah to Wong Chu, a Taoist who lives in the vicinity and who explains the philsophy to her, inasmuch as such things can be explained. Wong Chu believes that the Huang Ti Clinic uses Taoism and tai chi as gimmicks, but admits that it is possible to slow the process of ageing thorugh an understanding of how chi flows through the body. Wong Chu himself is nearly 80, though he appears to be in his late 30s. However, it’s said that lives can be extended through the use of dark sorcery...

Convinced that the Huang Ti Clinic is more than it seems, Sarah books rooms at a local B&B run by Mrs Lythe. As local girl Nellie cleans up, Sarah chats with her and learns that Nellie intends to apply for a position at Holtooth Hall. Claiming that she wants to play a joke on a friend, Sarah pays Nellie 250 pounds to postpone her application, and goes to the Hall in her place. Read nearly recognizes her from earlier, but not quite, and Sarah thus gets through to Nurse Jephson, claiming to be Nellie’s friend Daisy Grigson. Jephson, who doesn’t care about the differences between the local girls, assigns “Daisy” to clean away the lunch trays with her new co-worker Meg Hawkins. As they do so, a new client arrives; Sue Tappman, the model (as it were) wife of rock star Pete Tappman. Sarah manages to slip into the room while Sharpe is telling Sue about the clinic’s regimen, and watches as Sue drinks a meaty-tasting red draught which Sharpe calls “concentrated essence of chi...”

Sue also nearly recognizes Sarah, who once wrote an exposé of the fashion industry, but Sarah bluffs her way out of the encounter. Later, she tells Josh that she recognized many of the clinic’s clients, and they’re all multi-millionaires at least. She’s taken a brochure, which merely describes a watered-down version of the Taoist philosophy with no indication of how it could prove so effective within mere weeks. However, she also found an enticing locked door, and has determined that it’s possible to look into the room beyond through a row of skylights on the roof.

The next day, Sarah helps Josh to slip into the grounds so he can look through the skylights. Evading Jephson, Josh manages to get up to the roof without further incident, and through the skylight he sees two rooms; one is a laboratory, and the other is like a hospital ward with 20 naked men and women hooked up to drips and transfusions. Sarah gets the security code for the door when Jephson enters the room without noticing Sarah “cleaning” nearby, and as soon as Josh reports that the coast is clear, Sarah enters the room to investigate. What she finds in the “ward” horrifies her. Josh then warns her to hide, as Sharpe is pushing Butley’s wheelchair towards the lab. Again, Sharpe can barely tolerate Butley’s senile abuse, although Butley insists that dear, cruel Ron still loves him, really. Sarah hides as Jephson enters the lab and lets Butley and Sharpe in through the French windows, but once inside, Butley drives them both out again. Like Josh, they can see him through the windows, manouevring his hands over a bottle of “essence” and muttering odd incantations under his breath. It seems that Butley is using dark sorcery after all...

Later, at the B&B, over a breakfast of tripe and onions which Josh chooses not to share, Sarah explains that blood is being extracted from the “patients” in the ward, and that silk threads have been wound around acupuncture needles in the victims’ bodies and passed through the blood. The “essence” fed to Sue Tappman, and presumably to all of the clinic’s clients, is the chi-enriched blood of young men and women, who are aged by the process -- in Toby’s case, aged to death. Josh is bemused by Sarah’s reaction; she obviously cares deeply about what she’s found, yet can still remain detached enough to act without rushing in heedlessly. She explains that she picked this demeanour up from a friend.

That night, Josh and Sarah watch from hiding as an ambulance collects a body from Holtooth Hall and drives off. They follow it to the moors, where they split up to get a better view of the “paramedics” as they dig a shallow grave for the body -- but Josh gets a bit too close, and the thugs beat him up and take him back to the Hall. Sarah is unable to intervene, and thus calls Nat with instructions to go to the police should anything happen to her. She doesn’t want to involve them yet, for fear that the government will then arrange for Butley’s crimes to be covered up, and Nat is disturbed to learn that Sarah apparently thinks Josh is expendable. But Sarah fully intends to rescue him herself.

The next morning, Sarah slips back into the secret ward to find Josh lying on one of the beds, connected to the drips and pincushioned with acupuncture needles. She frees him, but the process has left him drained and disoriented, as though half-asleep and half-drunk. She gets him out of the ward and hides him on the grounds, leaving him to sleep until he’s fit enough to get back over the wall to safety. However, when she returns to work, Meg mentions having seen Jephson run out through the security door in a panic a moment ago. Sarah rushes back to Josh, wakes him, and gets him back over the wall and away to safety mere moments before the searching security guards find the ladder propped up against the wall.

Back at the Hall, Butley awaits his daily draught... but Sharpe has finally had enough of the old man’s abuse and dementia, and he withholds the draught, demanding to know the secret of the essence. Until Butley tells him the incantation which makes it effective, Sharpe will give him no further draughts -- and at Butley’s age, he won’t last more than 24 hours. Butley reacts with threats, pleading, and piteous sobbing, but Sharpe is only disgusted further. He leaves Butley to consider his options. Butley thus calls in Read, ostensibly to ask what the security alarm earlier was about. In fact, he knows how “obliging” ex-Guardsmen like Read can be with the right persuasion, but he’s not after sexual favours -- he simply wants to buy a gun, and he’s willing to pay 60,000 pounds, enough for Read to set himself up with a pub in the country. Read considers the offer, and admits that although he doesn’t personally own a gun, he can get one. For 40,000 pounds up front and a promise of more to come, tomorrow he will give Butley a gun and then take the rest of the day off.

The next day, once Josh has fully recovered, he and Sarah return to the Hall to confront Butley and learn the truth. This time, Josh enters the Hall with Sarah, lures Jephson into her office and knocks her out. Sarah disguises herself as a nurse and searches the room, which is full of historic memorabilia. She and Josh then hear shouting from the next room, as Sharpe demands the secret from Butley and Butley refuses to give in. His faculties are deteriorating rapidly, however, and he’s becoming more panic-stricken as he feels himself dying. Can’t Ron forgive him his abuse? Can’t they go back to how things used to be? Sharpe ruthlessly cuts through his illusions; before they opened the clinic, Sharpe was nothing more than Butley’s rent boy, and he knows what happened to all the others. He was only out for money; he never loved Butley the way Butley imagines, and was always sickened by what they had together.

Sharpe leaves Butley locked in his room and enters Jephson’s office. Fortunately, he doesn’t recognize Sarah, who passes herself off as Jephson’s replacement. Sharpe orders her to take care of Butley, but tells her to give him no medication unless Sharpe tells her to. Sharpe then leaves, but before Sarah and Josh can confront Butley, Read arrives. Josh grows impatient waiting and leaves the office too early, running into Read on his way out. Sarah joins in the fight and knocks Read out, using Venusian aikido techniques she learned from “an old friend.” She then confronts Butley and soothes the paranoid old man, assuring him that she’ll help him get whatever he wants from cruel Ron if he tells her everything. Butley confirms what she had already guessed; he is over 300 years old. Working as a clerk in Shanghai, he fell in love with a Taoist philosopher who taught him the secret of chi... and he then killed his lover and spent centuries luring young men into his clutches, having “fun” with them, and then draining their lives away to extend his own.

The enraged Sharpe arrives, drives Sarah out, and confronts Butley with a tape recorder he’d hidden in the laboratory. After years of tolerating Butley’s abuse, he has finally learned the truth about the “incantation”. Infuriated by all the time he’s wasted, he begins to throttle Butley, but Butley shoots him through the heart with the gun provided by Read. Butley begins to bawl uncontrollably upon realizing that he’s killed his darling Ron, but he’s even more concerned for himself. However, Sarah refuses to give him his draught, instead having Josh flush it down the sink as she plays Sharpe’s tape recording... and learns that Butley was only ever reciting “Mary Had a Little Lamb.” Butley dies of old age at last -- far too late, as far as Josh and Sarah are concerned.