Just Another Missing Person, Gillian McAllister

OLIVIA: 22 years old. No history of running away. Last seen on CCTV, entering a dead-end alley.  And never emerging.

JULIA: Detective Chief Inspector Julia Day ought to be out hunting for Olivia. After all, missing person's cases are a race against the clock.

Only this one is different. Because someone just threatened Julia: Find Olivia, and we'll take your daughter . . .