With the directorial presence of the Farrelly Brothers (Kingpin, There’s Something About Mary) and a backdrop that includes the bowel, one might have been forgiven for expecting Osmosis Jones to be cinema’s great scatological epic. As it turns out, the film has considerably more charm to it than we had any right to expect, and makes for an amusing and diverting kiddie flick, if one wholly unlikely to trouble Harry Potter And The Philosopher’s Stone in the box-office stakes.

Frank Dettori (Murray, as the film’s live-action protagonist) is in the unfortunate position of having devoured a rotten egg. At this point, (borrowing a conceit already familiar to anyone acquainted with The Beano’s Numbskulls) the story is turned over to the animated dwellers within his body, who must join together in order to save Frankie from the evil virus Thrax. As such, white blood cell Osmosis Jones (Rock), a cop on the City of Frank police force, teams up with cold remedy Drix (Hyde-Pierce) to save Frank from the villainous intruder, as they both become convinced that this is no mere common cold they’re battling against.

Warner Brothers were once reliable producers of the worst and most chronically unenjoyable animated fare kids could be subjected to (The King and I, etc.) Of late, however, the balance has begun to be redressed: The Iron Giant was a class act, and Osmosis is a similarly competent if comparatively low-tech animated adventure. As one might imagine, Rock and Hyde-Pierce make for a perfectly mismatched central pairing, with Rock finally having found a medium where his loud-and-large persona doesn’t become horribly grating. Equally, William Shatner’s turn as the City of Frank’s Mayor provides – ironically – his least two-dimensional performance to date. Clever casting aside, though, one can’t help feeling that more could have been made of Osmosis Jones, and it often seems overly reliant on that which is already tried and tested in both buddy-comedies and cartoons. There’s the added problem that it’s heavily dependent on the assumption that Bill Murray’s facial expression is inherently funny, and the Farrelly-directed action sequences are the weakest in the movie.

Still, if hardly original and far from inspired, Osmosis Jones is a reliably entertaining if thoroughly unessential experience.