When an attempt is made on a billionaire businessman's life, Professor T suspects the culprit may be much closer to home than the police suspect. It's Professor T's birthday and with it comes a haunting childhood memory.
Professor T befriends a vulnerable girl and is convinced she is the key witness to a murder. Dan and Lisa agree to go on a date but when her boss confronts her about their inappropriate relationship, Lisa makes a bold decision.
Lisa and Dan visit Professor T at his office where they show him a ransom demand they've received. A lock of Charlie's hair accompanies the letter, and after testing it for DNA they make an important discovery -- but Professor T is already a step ahead of them.
Professor T is called upon to help investigate the disappearance of a six-year-old girl. Tensions rise between DI Paul Rabbit and Prof T until they finally come to blows.
Professor T color codes tea bags in the police station while explaining how black diamonds, or carbonados, are thought to be created with the team. He later meets Ben, but the two quickly clash when Ben refuses to follow Professor T's three rules for hostage negotiations and leaves a used tea bag on the once-clean table.
Professor T becomes embroiled in a hostage situation, but his unconventional negotiating tactics do not go down well with the police. Old flame Christina reveals all is not well with her marriage.
When a blameless librarian is poisoned at a reception at the museum, Professor T is called upon to help narrow down the list of possible suspects, but not everyone on the police team is happy with Professor T's involvement in the investigation.
While carefully organizing his kitchen, Professor T receives a surprise visitor when he sees his mother at the door. When inquiring as to the reason for her visit, she reveals she's been making frequent stops by her studio in the garden in preparation for her upcoming exhibition.
Professor Jasper Tempest is obsessed with cleanliness, structure and order. But his genius for solving crimes means he constantly has to get his hands dirty, helping the police to crack their most difficult cases.
Obsessed with structure and cleanliness, Professor T conducts his morning routine by thoroughly cleaning his hands, putting on his rubber gloves, and precisely measuring out his morning coffee to prepare him for the day ahead. Walking to work, he passes by his abandoned childhood home where he reflects on a troubled youth.