London's Second City has been the scene of many a terrifying crime, but the discovery of a pile of infant skulls unearthed near police headquarters is particularly horrifying. Another major worry for John Coffin, Chief Commander, is a triple murder on his patch, that of a midwife and her two daughters. The obvious suspect is her son, Black Jack Jackson, a local villain, but both Coffin and DI Phoebe Astley are reluctant to accept his guilt. Two further murders add renewed urgency to both investigations: one of a doctor, discovered in a hospital laboratory surrounded by grisly trophies, might well be connected to the disinterring of the children's skulls; the other, of a notorious Second City criminal, with the brutal midwife killings. Coffin is able to take all this in his stride, however, until the growing violence comes closer to home - directly threatening the safety of his wife, the actress Stella Pinero.