When a palliative care doctor and her husband and two children are all found dead in a grisly tableau on their living room sofa, the Police ask Professor T to help them decipher how they died, in what order and at whose hands. Is it a text-book case of ‘familicide', in which one of the parents has murdered their partner and children or was a disgruntled third-party involved, given the doctor's outspoken support for assisted killing to let her patients die with dignity? As the investigation proceeds, Lisa is forced to confront the truth about her father's dementia and she finally shares it with Dan, bringing them closer together than ever. Challenged by Dr Helena to face his fears about his past, Professor T enlists help from Adelaide and Ms. Snares to confront his phobia of intimacy, but with extremely mixed results.

Professor T conducts a series of lectures for his students detailing a high-profile court case in which a caretaker is accused of murdering his employer; the accused was found standing over the victim's body and his fingerprints on the murder weapon, but Professor T is convinced of his innocence, bringing him into conflict with the CID team and DI Paul Rabbits as the investigating officer. As Professor T persuades Lisa to go behind Paul's back and help him try to prove his case, he starts to shine a different light on the prosecution's evidence. Lisa tries to soften the blow to Dan of her upcoming promotion but only succeeds in making things worse. Adelaide agrees to Dr Helena's request to take part in a joint therapy session with her son to try to help him understand the root of his hostility towards women, but conflict ensues.