Andy (Brydon) is a struggling actor who once co-starred in a sci-fi series called "Children Of Castor" alongside Nick (Coogan) who had quite a talent for casting rather large shadows over his co-stars, particularly his ex-mate Andy. Push comes to shove as Andy finds himself out of work and lugging luggage around at a hotel when he's suddenly approached to attend a "Fan-Cruise" with a bunch of sci-fi nerds who are still obsessed with his now obsolete series. As you can imagine he finds it very difficult to refuse the offer, even though it'll mean tolerating the high-and-mighty antics of not only Nick, but also the cruise coordinator Lurky (Walliams).