The Mind Has Mountains

A student dies during a college-based clinical trial of a new anti-depressant, and the immediate question is whether the death was murder or suicide. The institution's psychiatry professor, whose judgment the whole trial calls into question, proves frustratingly evasive, and Lewis and Hathaway get little help from the side that ought to know most. Then a second student dies under similar circumstances, and the picture sharpens into something alarming.

The trial's participants, it emerges, have all been operating under the influence of ketamine, a mind-altering drug that has done more than cloud their moods. The lines between love, obsession and madness have become dangerously blurred, and the deaths start to look like the logical end of that confusion. The episode does not flinch from the mess, watching bright young people come apart inside an institution that was supposed to be helping them.

But the episode does not lecture; it simply lets the evidence accumulate until the ethics of the whole enterprise are impossible to defend. A college testing drugs on its own students and calling it progress is a quietly damning subject, and the show lets the trial condemn itself.

Colin Dexter and Patrick Harbinson wrote it, and Charlie Palmer directed. Douglas Henshall plays Alex Gansa, Jack Roth is Jack Collins, Nichola Burley plays Karen Wilde, Florence Brudenell-Bruce takes Amy Katz, Sophie Stanton plays Shauna Malin, Thomas Brodie-Sangster is Adam Douglas, Lucy Liemann plays Bethan Vickery, Christina Cole takes Claire Gansa and Sam Hazeldine plays Dane Wise. Laurence Fox and Kevin Whately lead the investigation.

The drug-trial setting gives the show something genuinely uncomfortable to work with, an academic story with a clinical, modern horror at its centre. There is no neat villain in a library here; the danger is pharmacological, and the victims helped dose themselves. It makes for a taut episode about how fragile people become when reality itself stops behaving.