Jeff ill-advisedly offers to clean the chaotic drains of his girlfriend Corinne while she's away at a pest control conference.

Seeking to free himself from this unsavoury task, Jeff strikes a murky deal with Fish Shop Frank to swap DIY tasks: Frank will clear Corinne's drains and Jeff will fix Frank's shelves. However, things don't go according to plan. The hapless pair are sucked into a swirling vortex leading to a seething netherworld of crime and Mariachi. Along the way they once again meet punctilious and pedantic policeman, P.C. Clarke ("That's Clarke with an 'e'"); and also unorthodox and erratic limo driver, Psycho Pete. In the meantime, Andy is training to be a bingo-caller: Unlucky for some - 13.