Ron Howard continues his charge into the realm of great commercial directors, this time supported by the considerable talent of Russell Crowe and the suddenly all-grown-up beauty of Jennifer Connelly.

John Forbes Nash (Crowe) is a brilliant mathematician on the verge of an astounding discovery, one that will transform financial market theory around the world. Unbeknowns to anyone, however, he's also schizophrenic.

While working at the Pentagon, a shadowy agent (Harris) recruits him to break codes in the mainstream American press and dismantle a Communist conspiracy to bomb America. Coming slowly unhinged and feeling the strain as his clandestine lifestyle threatens the security of his life and new marriage to former student (Connelly), he is committed to a psychiatric hospital.

There both he and the audience learn the horrible truth (and we're treated to a shocking and very effective twist). His government benefactor (and the job Nash does for him) and his best friend from Princeton college don't exist - constructs of his deluded mind when he desired understanding of his struggle at college and more interesting work seconded to an aerospace contractor.

When medication threatens to end his marriage, he makes the pivotal decision that makes his story great when he could have been another slobbering madhouse inmate. Choosing to ignore the people he knows are visions, he is able to lead as normal a life as he can, leading to the Nobel Prize for his theories in 1994.

What's clever about the script is that everything Harris describes as the Communist threat is just a bit hokey, just a bit far fetched. It left me thinking Ron Howard - usually such a realistic director - had dropped the ball. To find out the whole thing was the product of Nash's imagination makes you realise how subtlely the delusions are portrayed.

The makeup is great portraying Crowe as a man in his seventies. The mannerisms he employs to portray Nash's idiosyncracies are good but a bit too forced. Connelly has never looked further from the teenage angel she was in Labyrinth, and the supporting cast live up to their positions in the plot well.

What looked like a run of the mill drama turned out to be a pleasant surprise.