It is 1942, and struggling up the hill to the new Kent military hospital Heron's Park, postman Joseph Higgins is soon to deliver seven letters of acceptance for roles at the infirmary. He has no idea that the sender of one of the letters will be the cause of his demise in just one year's time.
When Higgins returns to Heron's Park with injuries from a bombing raid in 1943, his inexplicable death by asphyxiation in the operating theatre casts four nurses and three doctors under suspicion, and a second death in quick succession invites the presence of the irascible-yet uncommonly shrewd-Inspector Cockrill to the hospital. As an air raid detains the inspector for the night, the stage is set for a tense and claustrophobic investigation with a close-knit cast of suspects.
