Linzi Birrell and Rhian Douglas: murdered.

Angela McCabe and Josh Norbury: murdered.

A killer the police have dubbed Billy Dead Mates is killing pairs of best friends, one by one. Just before each murder, he sends his victim a small white book…

Three regional police forces are working together to identify and catch Billy. For five months, they’ve been failing. Then a fifth victim, scared by what she’s seen and heard on the news, comes forward to seek help. Unlike Billy’s first four victims, she isn’t dead. Yet.

Stand-up comedian Kim Tribbeck has one of Billy’s peculiar white books. A stranger gave it to her after a gig she did a year ago. Was he Billy? Now Kim’s life depends on working out why she - a woman who has no close friends because she trusts no one - should attract the attention of the Best Friends Killer… And, if Billy has her in his sights, why has he waited so long to strike?