On the ride back from a job interview in London, one of Martin's patients dies in the next seat.
Martin is in London to meet with Robert Dashwood, who is leading the selection process for the prestigious London surgeon's job that he has applied for. Pleased that Martin has finally conquered his debilitating blood phobia, Robert is confident that Martin will be hired. On the train back to Cornwall, Martin is annoyed to be seated next to one of his patients, a sheep farmer named Jim Selkirk. Jim falls asleep and slumps onto Martin's shoulder - dead from heart failure! Theo, one of Louisa's students, becomes ill in class. His parents, Juliet and Richard Wenn, are certain that their child picked up the illness in Joan's chicken coop during a school field trip. Martin cannot deny it is a possibility and the couple announces their intention to sue Aunt Joan. Mrs. Selkirk returns to Martin's Surgery, and tells him she is now seeing visions of her dead husband. When she is found collapsed in her sheep pen, Martin is able to uncover the medical reason behind her hallucinations. When he receives Theo's test results point to Joan's innocence and Martin is finally able to identify the real source of his sickness.