Andy Van Allen (Rob Brydon), the former hero of a cult 1980s futuristic TV show, Children of Castor, is now working as an hotel porter. In contrast, his ex co-star, Nick Lee (Steve Coogan), has since shot to fame in the USA starring in a blockbuster mini-series, Sherlock Holmes in Miami.

Things start to look up for Andy when an unusual offer comes along; the Children of Castor Fan Club has organised a fan cruise and invite him to attend as the principal celebrity. Once aboard however, a combination of Andy's cynicism, his fans' adoration, a misguided sexual encounter and an unexpected death ensure the paradise cruise is far from plain sailing.