Dido Hoare, antiquarian bookshop owner and single parent, is walking her young son home from nursery. When Ben tells her he has seen a monkey, she assumes it is a figment of his imagination. However, Dido suddenly remembers having met both a monkey and its owner, one of the rough sleepers in the neighbourhood, and her duty seems clear: she must restore the poor animal to his master. Dido does recover the lost monkey, but its owner only reappears briefly when he finds the dismembered body of a girl in a pile of rubbish sacks across the road from the shop; and although he escapes from police custody and then leaves some of his belongings in Dido's dustbin for safekeeping, he is found injured in the street nearby, supposed victim of a hit-and-run accident. This bewilders not only Dido, but the local police, and journalist and heartthrob Chris Kennedy who is in the midst of a newspaper investigation into people-trafficking, and even Dido's father, Professor Barnabas Hoare. Before long, others complicate the problem: DC Ken Acker, who seems to be playing his own game; his injured wife, one of Dido's oldest customers; two thugs who invade the bookshop; a girl called Nina; and above all Annie Kelly, the retired prostitute trying to make her way in the world with the help of some shoplifting and a bribe from the journalist, Chris. After that, things become a little confusing, and working them out takes all the help and courage Dido can find...and a little more.