Apocalypse Slough: A Murder, They Hope Mystery sees Gemma recruited by the Serious Crimes Agency (SCA). It's a dream come true for the ambitious sleuth, who can finally live as the kick-ass investigator she always dreamed of being... but unfortunately the SCA don't want Terry because of his criminal past.

As Gemma's new status puts a strain on the couple's relationship, they are hired to solve a double murder at a local rugby club, where all of the members seem to be behaving very strangely — and then more bodies start appearing.

To make matters even weirder, the dead bodies all bear the same strange symbol somewhere on them — could this be a gentleman murderer leaving a calling card? And why does a camouflaged figure keep calling Gemma from a mysterious bunker?