Georg Trotter, a former football player, has been a lifelong advocate of clean football. Highly feared as a doping hunter, the football industry named him "Bloodhound." But there isn't much left of the feared "Bloodhound." A car accident ten years ago drastically changed his life: His wife Diana has been confined to a wheelchair ever since, and the couple lost their son Ben. Meanwhile, disillusioned, he works as a doctor in a middle-class hospital in Liverpool, where he performs routine operations. He now does doping tests for the regional leagues, never moving far from his wife, Diana Trotter, who was a talented and successful investigative journalist before the stroke of fate. Nowadays, she masks her grief and bitterness with red wine and cynicism. An invitation to Austria from Andreas Müller, a former teammate and good friend of Georg's, comes as a surprise and yet at the right time. In the Austrian mountains, he is to manage a state-of-the-art sports clinic called "Clinic Performance." Georg is unsure, but the clinic's investors want him as a head doctor. They want "the Bloodhound," who will help them in their crusade for clean football. Diana and Georg are skeptical but accept it out of desperation for a fresh start. A series of interlinked events begin around the couple. Georg confronts his past. He decides to look into his accident when Jeremy Hall, a former colleague, reveals that the fatal car accident was a targeted attack on him and his family. While Georg struggles with whether to share his new knowledge with Diana, the seriously ill Jeremy Hall gets suspiciously murdered in Liverpool.

While still in Austria, Georg receives a call from Erika Green, a Merseyside Police inspector, who informs him that Jeremy Hall has been found dead. Georg is shocked. Even though he knows that Jeremy is in poor physical condition due to his advancing cancer, the sudden death of his former colleague strikes him as strange. Detective Green wants to question Georg personally after his return to Liverpool, as he was the last person Jeremy had called. But for now, Georg decides to concentrate on the clinic. He meets up with all the investors: hotelier Franco Casutt, pharmaceutical couple Clara and Klaus Fischer, Chinese businessman Chai Dan and his niece Anne Hsu. Diana, in the meantime, meets with Edmunda Cerna, a highly respected biochemist who works and researches at the clinic. She tells Diana there is an enzyme that could help her walk again. As much as she longs for her old life back, she contemplates becoming Edmunda's lab rat. While flying back to Liverpool, Georg tells Diana about Jeremy Hall's death and his claim that the accident was an attempted assassination. Diana refuses to believe it. In England, Georg learns that the last doping samples he had personally supervised are unusable. Allegedly, the cold chain had been interrupted. Georg suspects the samples were deliberately destroyed to cover up a doping case. Things are not much better at his workplace in the hospital either: Georg's conflict with his superior escalates. Diana investigates Jeremy Hall's allegations and meets Mary Perkins. The journalist wants nothing to do with it anymore. Instead, Mary gives Diana a first glance into Jeremy's not-so-flawless past. Diana senses that she is on to a story for the first time in a very long time. DCI Erika Green and her associate Sgt. Ian Sabel has to face another body discovery: Betty Chong, the young Asian woman who murdered Jeremy Hall, is found dead.

It is Georg's first day at work at the Clinic Performance. He meets Edmunda Cerna, who is performing some tests on the young footballer Henri Tadjou. Andreas introduces Georg to his first patient: Emmanuel Kanu, a professional footballer who injured his knee in training, accompanied by his agent, the well-known talent scout Richard Felgenbauer. Kanu's knee injury is not the first of its kind and requires immediate surgery. Georg gets into a conversation with Henri Tadjou, because Henri reminds him of his deceased son Ben, who would now be the same age. Henri is desperate because he does not meet the demands and requirements of competitive sports. Suddenly, out of the blue, Henri collapses. As there was no external trigger, Georg requested a doping test. In Liverpool, Erika Green attends the autopsy of the two bodies of Jeremy Hall and Betty Chong. It turns out that both were poisoned with Levofentanyl, a highly potent poison used mainly by intelligence agencies. Chai Dan instructs his niece Anne Hsu to make her lover Franco Casutt a middleman to establish a World League. Diana decides to pay a visit to Jessica Hall, learning that during Jeremy's time as a coach for the Rovers youth team some ten years ago, there was a sudden onset of mysterious deaths or illnesses. Diana confronts Jessica about her car accident, but Jessica denies it. After a brief phone call with Georg, during which it emerges that he should have been testing this very football team 10 years ago, Diana becomes even more suspicious. The Rovers' groundsman, Cameron Rea, gives Diana startling insights into Jeremy Hall's life that reinforce her theory. Diana's house gets broken into, and the Trotters' Liverpool home gets vandalized. Erika Green asks her if she would be better off leaving the investigation to the police. At the clinic, Georg learns from Edmunda that one of the investors, Franco Casutt, wants to stop or even turn back the clock on life. He realizes that the clinic is probably not only focused on young athletes. Hidden from Georg, Edmunda sequences Henri Tadjou's DNA - under the constant observation of Clara Fischer. Richard Felgenbauer gives an ultimatum to Georg that Kanu has to play in the upcoming world championships. For Georg, this is an impossibility, but the agent insists.

Georg Trotter fears for the life of the young player Henri Tadjou. Delirious, Henri tells him something about the 2010 World Cup and that he played well there. When the timeline does not add up, Georg begins his research. He realizes Henri would have been 21 years old during the 2010 Cup, baffling him even more. As the footballer's condition deteriorates further, Clara Fischer orders to have the player flown to the nearby hospital without Georg's knowledge. For the first time, Georg has to make the hard choice of protecting not only the clinic's reputation but also his reputation and career. Andreas asks Georg to keep Henri's illness a secret. Diana is in Liverpool preparing to move to Austria but she can’t seem to let go of Jeremy Hall's death. After learning from the Rovers groundsman that other players died ten years ago, she contacts Jessica Hall again. Edmunda continues to work at full speed on sequencing Henri Tadjou's DNA. Henri's unexpected breakdown leads her to a breakthrough in her research, which soon gets around the clinic: in addition to Clara Fischer, Anne Hsu also shows interest on behalf of her uncle. The sports clinic is expecting an important visitor: Jean Leco, the president of the WFA, wants to visit the clinic informally. Franco Casutt (as an instrument for Chai Dan) uses the opportunity to buy his way into the World League - for 75 billion euros. Edmunda tells the upset Georg what the goal of all this is: a drug against aging, an enzyme for eternal life. When Chai Dan collapses suddenly, Georg and Andreas perform emergency surgery to save his life.

Diana hovers between life and death, between Georg and Ben. At the last second, she gets revived because the doctors, through Erika Green, know what they are dealing with: Levofentanyl. The chondroitinase ABC administered by Edmunda secretly contributed to her recovery. Diana seems to feel more again, and her pain indicates a change in her body. Even though Georg, who has arrived in England, finds it hard to leave his wife alone, he goes to the EAD and confronts his former colleague Bryan Patel. He finds out what drove the young Rovers players to death and disease ten years ago: an enzyme that interferes with the genetic material. Chai Dan is determined to find out who is behind the attempt on his life. Anne Hsu subjects Fritz, the clinic's majordomo, to Ling Chi - the art of performing as many cuts and amputations as possible without the victim dying to find out on whose behalf he switched her uncle's pills. Detective Erika Green meets a man, Paul. The two hit it off right away. A glimmer of hope emerges alongside the everyday life of the investigation and the constant fear for her drug-addicted daughter Ava. Edmunda is at the finish line. She and Clara Fischer can finally inject themselves with the first two doses of the new enzyme. When Andreas Müller shows up at Diana's bedside, something major comes to light: there's something that connects the two. Georg gratefully accepts that Andreas is here to take Diana to the clinic in Austria for safety. During the flight, Georg tries to question Andreas about Henri's collapse. But his old friend refuses to answer straightly, reiterating that one has to accept sacrifices. Back in Austria, Georg starts looking for Henri Tadjou and goes to Vienna. There, Georg learns that the terminally ill Henri is supposedly in perfect health and was acquired by a new club.

Georg realizes that Henri Tadjou is no longer in Vienna but moved to the Hungarian FC Baja. He sets off for Hungary. He has to find out what happened to the boy as he feels responsible both as a doctor and a human being. Diana is getting better: as she learns from Edmunda, she also survived because of chondroitinase ABC - the lack of oxygen even encouraged it. Parallel to Georg, she tries to find out more about Henri Tadjou: She learns from Eva Rieper that Kanu is miraculously better and that his advisor Richard Felgenbauer is just here to pick up Emanuel Kanu. Edmunda Cerna can hardly savor her breakthrough about the enzyme for eternal life. She gets pressed from all sides - everyone wants the enzyme: Chai Dan makes it unmistakably clear to her that she has to choose the right side, and Clara and Klaus Fischer also want to secure their investment. It seems that only Andreas Müller remains for her. The battle for the last batch of the enzyme begins. In Hungary, Georg finds the club FC Baja, only to see an abandoned, overgrown football pitch. It's a trap - Thugs waiting for him there escort him back to the border. Erika Green finally makes progress in the investigation surrounding the events at the Rovers ten years ago: former Rovers player Liam Dunkley agrees to give a blood sample to search for the ominous enzyme with which the youth players were doped back then. He is also willing to produce a sketch of the persons who had administered the enzyme to the players. In addition, the Liverpool police finally find traces of the second murder victim, Betty Chong, in a hotel room. Searching the room reveals a cell phone that has one number stored in it - Chai Dan. But Erika stops going further because she receives a phone call: her daughter Ava got kidnapped. While she does save Ava, she realizes the threat enough not to pursue the case any further. To cover herself, Edmunda gives Diana a USB stick with the instructions for building the enzyme. When Georg returns to the clinic, he angrily confronts Andreas about Tadjou's disappearance and everything going on. But the argument ends abruptly when the two learn that Clara Fischer needs an emergency cesarean section. Georg fights for the life of the mother and child in the operating room.