One young woman is strangled as she lets herself into her flat, while across town another wakes to find her boyfriend has been shot while she slept.

DI Susan Alembic and DS Luke Stone investigate the sniper-shooting of a young man in his flat, while DCs Alison Bain and Frank Craven deal with a hit-and-run killing.

A teenaged girl is found dead in her school with her wrists slashed, while a man has been tied to a tree and shot dead in the woods nearby. Stone and Alembic lead separate investigations, but is there a connection?

A teenage couple kiss one another goodnight when the dead body of a woman is thrown from the top of an apartment block, killing the young man. DC Bain links the dead woman to a dating agency for married people, and DI Alembic goes undercover as a client.