Friday afternoon, and the traffic is bloody murder.

Sergeant Belinda 'Billy' Kidd is driving home from the airport, jet-lagged and ready to resign from a career that has left her traumatised. Menopause has robbed her confidence too - now she's a traffic cop who's afraid to drive. When brake lights hemorrhage up the motorway, the cars grind to a halt. Moments later she finds a dead driver in a black sedan.

He has a metal skewer in his neck. But how? The killer can't have left the scene without being spotted by the dozens of witnesses—so he must still be there, among them. If the traffic jam stays put, they're all in danger; if the traffic clears, she'll lose her suspect. The clock is ticking, but she doesn't know how fast.