DCI Adam Dalgliesh is sent to a nursing school to investigate the death of Heather Pearce, a student poisoned during a demonstration. But as he uncovers the secrets that infect the school, can Dalgliesh identify the killer before they strike again?

After the death of another student nurse at Nightingale House, Dalgliesh's hunt for the murderer intensifies. A private patient who died at the on-site hospital might hold the answer, but Dalgliesh's curiosity puts his own life in danger…

March 1975. Dalgliesh is invited to Dorset by his old friend Father Michael, only to discover that he died a few days ago. Father Michael lived in a home for the disabled run by the enigmatic Wilfred, who has organised trips to Lourdes ever since he was miraculously cured there of a serious illness.

Wilfred announces that he will transfer the Grange to the Ridgewell Trust and hold a vote on whether he will carry on as spiritual adviser. Maggie threatens to down the ‘whole rotten place’. Despite Eric and Helen’s plot to usurp Wilfred, the majority of the Grange vote for Wilfred to stay, ensuring the Lourdes trips will continue.

May 1975. 8-year-old Darren and churchwarden Miss Wharton find two dead bodies in the vestry of St Matthew’s Church, Paddington, their throats slashed. One is Sir Paul Berowne, a baronet and recently-resigned Tory MP; the other a homeless man called Harry Mack. Dalgliesh is called in to investigate, accompanied by DS Masterson and his new DS Kate Miskin.

After the attack on Father Barnes while Halliwell was in custody, Dalgliesh brings Swayne and Lampart in for questioning. He discovers Lampart is having an affair with Lady Barbara, who reveals she is pregnant and thinks she will inherit everything. However, Lady Lavinia reveals that Sir Paul secretly changed his will at the last minute.