Self-Awareness & Growth Mark 'Professor T's "A Little Drop of Poison"

We teach best what we most need to learn; this week, Jasper is the perfect example of this idiom, gaining wisdom and (eventually) embracing humility in Professor T's fourth episode. He haunts his old lecture hall – both when empty and when occupied by his replacement, Erik Haiden (Cornelius Booth), whose students look bored. In his first session with Dr. Goldberg since his release from prison, Jasper is rude, dismissive, and superior. He declares she cannot be impartial about the assessment the police requested before he’ll be allowed back as a consultant. 

He scoffs when Dr. Goldberg worries about suicidal ideation, which she says often accompanies a loss of status. When the hour is over, Jasper ends their relationship, claiming there’s nothing more he can gain. Dr. G says he hasn’t progressed enough, but he argues it’s her failure, not his. In a fascinating moment, Dr. G provokes Jasper enough that he sits down without first laying out his handkerchief – something that might otherwise be an OCD breakthrough, but he is too bull-headed to notice.

When Jasper discovers he isn’t getting his professorship back, he returns the box of chocolates Ms. Snares gifted him: “Since I am neither welcome nor back, these cannot be mine.” Ms. Snares is angry about Jasper not returning and shoves the chocolates at the Dean, telling him not to choke on them. He then regifts the chocolates to Adelaide. (This odd bit of hot potato comes back into play later.) 

We start with a victim named Amara (Chanel Fernandes), who we see come home from a jog, take a swim, and then begin to feel sick. She vomits, seems to faint, then falls over a balcony to her death. The police hear her last phone call to her boyfriend and think she sounded drunk. 

Back at the precinct, Donckers is distracted and worried about her father and her recent decision to put him into assisted living. She’s annoyed and questions why they’re on the scene of a death that is not suspicious. Donckers is admonished for her attitude by a woman in a tracksuit who turns out to be Christina’s replacement: the new boss, DCI Maiya Goswami (Sunetra Sarker). The case quickly heats up with five additional victims who all vomited before dying. The police suspect poisoning but can’t find any links between the victims. Jasper misses meeting Goswami but jumps in to help the team, who still believe intoxication was involved. Jasper tells Donckers to research substances that mimic drunkenness, and she discovers the likely culprit: ethylene glycol. 

Jasper posits the poison’s delivery system was chocolate. Bad news says the police lab: it’s only possible to find the food used as the carrier if it was plant-based; otherwise, the evidence dissolves in the victims’ stomachs. Still, Jasper and the police follow his hunch to Harwood’s chocolate factory, where one of the victims was a co-owner. At the factory, they discover a worker, Ferdy Walters (Jonny Lavelle), acting suspiciously and arrest him when they find amphetamines in his car.

Jasper meets Goswami when they return from the factory and asks her to assign his assessment to another psychologist. Goswami doesn’t need one to make up her mind: she says they won’t need his services anymore. Jasper is shocked; Donckers is angry. She continues to work with Jasper on the side, taking his advice to interview Justin Dennis (Robert Maskell), a man who was cut out of the partnership with Harwood’s and whom Jasper is sure used Ferdy to contaminate the chocolates. Shortly thereafter, the lab found a match: each victim had eaten raspberry-infused chocolate. (Unless the raspberry was a considerable percentage of the chocolate, doesn’t that negate the lab’s earlier statement that the carrier would be impossible to find?) 

The lab’s head tech Dixon (Adam El Hagar) is terrified; he recognizes the candies as Harwood’s signature Redcaps which his wife loves to eat. He rushes home and finds, too late, that she has also died from the poison. Traces of ethylene glycol are found on Ferdy’s money; the police press him to confess. Donckers posits Ferdy wanted revenge on the owners who cut his pay. Despite the evidence, they don’t think he meant to kill anyone. Ferdy swears on his daughter’s life he thought he was injecting the chocolates with laxatives as payback against his boss for lost wages. The police pressure him: Who supplied the ethylene? It was Justin Dennis, who is holding Ferdy’s daughter hostage.

A tip from Jasper leads Donckers and Goswami to Dennis at his holiday cottage. Echoing wisdom from Dr. Goldberg, Jasper notes that people who experience a loss of status gravitate towards places they associate with success. Working together, Donckers and Goswami disarm and arrest him. Ferdy’s daughter is safe, and Jasper’s tip saved the day, but Goswami is still adamant he’s unstable and isn’t allowed back.

Jasper learns Dixon’s wife was the last to die and personally questions him about who bought his wife the chocolates. He claims she bought them herself from Graham’s Mini-Mart, which makes Jasper suspect Dixon murdered his wife. Furious that Jasper overstepped his bounds while not officially on the case, Goswami tries to prove him wrong and finds CCTV footage of Dixon’s wife buying the Redcaps – but on closer inspection, it is actually Dixon dressed as his wife. 

Upon arrest, Dixon admits to killing her but insists it was kindness: his wife was dying of a degenerative disease, and he spared her more suffering. Though possibly true, there’s a coldness to his premeditated act and a question as to whether his wife consented.

Jasper comes to realize not all of the poisoned Redcaps have been found. The last unaccounted-for, tainted chocolate is in Adelaide’s possession – the box Ms. Snares had initially purchased for Jasper. He races over in time to see her holding a chocolate with a bite out of it: her beloved dog Kafka has eaten the poisoned candy. For a horrible moment, the little chihuahua lies still on the carpet, but mercifully, he vomits up the candy and is just fine. “Clever dog!” Adelaide praises. “He saved his mummy’s life!” Jasper retorts that Kafka just wanted the chocolate. 

• Goswami tells Jasper she’ll allow him to continue consulting on a probationary basis. What made him suspect Dixon? He doesn’t believe in coincidences, he answers. 
• Early in the episode, Goswami confronts Donckers and Dan about their relationship and mandates that one of them apply for a transfer. Donckers thinks they can win her over with their team performance, so both of them can stay.
• Character growth! Once the case is solved, Jasper resumes his therapeutic relationship with Dr. Goldberg, admitting he sees an opportunity to learn. So it wasn’t jail that humbled him; it was the fallout from status loss.

Professor T Season 3 airs at 8 p.m. ET on Sundays on most PBS stations, the PBS app, and the PBS Masterpiece channel through the end of July. All six episodes are available as a binge for members on PBS Passport. As always, check your local streaming service/listings.