Fans of The Big Bang Theory will view the casting of Jim Parsons, who plays the socially-inept genius Sheldon Cooper on the hit TV show, as a brilliant move. Oh (Parsons) is a Boov, a six-legged purple alien whose leader has moved the entire species to Earth to escape the enemy race, the Gorg. The Boov are the best species, Oh says - at running away. Every time they fear the Gorg are going to capture them, the Boov move to a new planet to hide. They're very nice to the current inhabitants - this time they move all humans to Australia, aka Happy Humanstown, and take over the rest of it.
All humans, that is, except Tip (Rihanna) who managed to stay put. She and her cat, Pig, are trying to survive, and to work out how to find her mum.
When Oh accidentally invites the entire galaxy - including the Gorg - to his "warming of house" party, he has to embark on an epic journey to find Tip's mum and try to recall the email before it reaches the Gorg's inboxes.
As with Sheldon, there's a lot of human interaction Oh just doesn't get, and seeing him understand the meaning of friendship, the importance of honesty and the power of dance is satisfyingly sweet. The film is a bit overlong, but its messages of looking beyond stereotype and discovering the true meaning of "home" make up for that.