It's a crazy Halloween night at Grimsby’s custody facility. The Joker and Harley Quinn are checked in for assault. A ‘welcoming party’ is needed for a violent detainee. Whilst Gangsta Granny is looking forward to her 'holiday' in a cell.
A full moon stirs up strange behaviour in Grimsby. Three men are arrested after a pub fight. One man knocks himself out in a police van and another can’t remember why he’s in custody. A ‘frequent flyer’ returns for the 74th time.
Practical jokes keep spirits up as the team tackles a violent detainee striking out at officers. Sergeant Jason hasn’t time to celebrate his 50th birthday as he must pacify an aggressive woman who’s kicking and screaming after being arrested.