After six months in an institution Professor T is released on one strict condition. Daan returns to the office, but things are not easy and Annelies' guilt puts their relationship under strain. However, the old team are back, and their help is needed; a number of fatalities have been linked to eating poisoned sweets, and the trail leads to the manufacturing company.

A student suffers life-threatening injuries as the result of an arson attack, and quite a few people appear to have motives for the attack. Dr. Gijselbrecht sets Professor T an assignment, however Professor T has other concerns. It has been decided that Professor Van der Weyden will continue to teach Professor T's course, but Van der Weyden has a secret.

A physician, his wife and two children are found dead. It is unclear to the team which one of them was the killer of the other three and therefore which of them committed suicide. Professor T is having nightmares and suffering from hyperventilation; is this a result of his therapy? Annelies makes a shocking discovery about her father and Rabet receives startling news.

A series of attacks have been carried out on SUVs. At the same time, pamphlets are being distributed for an anarchist student group which Professor T was once a member of. Professor T invites Flamant to his home for dinner which does not go as planned. Daan's replacement John joins the team; he is certainly an asset and proves intelligent enough to compete with Annelies.

Having witnessed more poor teaching by Van der Weyden, Professor T is at his wits’ end and comes up with a plan to pretend that he is considering a job offer at a different university. Annelies realizes she can no longer take care of her father on her own, and has some tough decisions to make. Annelies and John are collaborating successfully, but Annelies still has her guard up.

A jeweler's family is taken hostage while the jeweler is on his way to empty the safe at his shop; an accident en route raises suspicion. Professor T is going through a rough patch and considers quitting therapy. Not only has he been unable to prevent a fatality, he's also admitted to hospital after an accident at a public swimming pool. Since his departure, Flamant has assumed Rabet's duties.

Jitske, a 17-year-old girl with Down syndrome, claims she knows who murdered her mother, but she doesn't want to say who it is. When Annelies shows insensitivity towards the girl, John decides it's time for her to meet his daughter, Elke. Professor T finds that Flamant is being overly friendly and it is making him nervous, especially when she confides in him about her upcoming divorce.

When a woman's body is found 100 meters from where her car fell into a deep canal, the cause of death seems clear. However, when it is discovered that her injuries were not caused by the accident the team struggle to come up with an explanation. Professor T receives a blow to his ego as Annelies struggles to accept her father's fast deterioration.

Much to the dean's dismay, Professor T refuses to appear as the second speaker at the annual conference of criminologists. Following the murder of the headliner, the event descends into disarray. Annelies and John's relationship improves, he has gained her trust: she tells him that she burned her father's living will and that she now regrets it. To her amazement, John has a simple solution.

Professor T's classes are proving popular. The material he presents is like a thriller that has the students on the edge of their seats and they start flocking to his class in increasing numbers. Annelies receives confirmation that her father's euthanasia request is legally valid and that she has been named trustee. Struggling with this heartbreaking decision, she turns to John for support.

A student at a strict Catholic boarding school is found dead in her room. At first the team assume it is a case of erotic asphyxiation gone wrong, but could there be another explanation? Gijselbrecht and Flamant have an interesting meeting. Annelies' father is laid to rest and her colleagues are there to show their support along the way. Rabet returns.

An undercover agent, who is embedded in the drug scene, is found dead in the trunk of his car. The target of the investigation is drug lord Mark Desmedt, but could this be too obvious a suspect? At the university it is Professor T's birthday, catalyzing his odd behavior and visions. Meanwhile Annelies' career comes to a crossroads and she makes a big decision.

While the team is closing in on drug lord Mark Desmedt, John discovers that Chief Inspector Rabet and Serge are both working with the criminal. Professor T asks Annelies to assist him with his research in determining the exact profile of a murderer. He wants to find out whether Flamant will be capable of murder when she finds out that her new boyfriend is not what he appears to be.