YOU won't find men in tights or riding horses in this castle - it is a modern military prison but described as a castle by three-star General Irwin. He has been sent there in disgrace after making a military blunder.

Just why he sees the place in this way is developed gradually in this rather intriguing psychological drama that curiously develops into an action movie.

At its centre is the story of two men, the General, played in noble fashion by Robert Redford, and the prison warden Colonel Winter, a complex character as portrayed by The Sopranos' James Gandolfini.

When the General first arrives at the prison, Colonel Winter is in awe of his new prisoner, inviting him into his office and asking him to sign one of the General's books he has in his collection.

But while he's getting the book, he overhears the General criticise his collection of military memorabilia, claiming that only a man who had never been on a battlefield would build a collection like it.

Suddenly the Colonel's attitude changes - he brusquely claims he cannot find the book and demands that the General be treated like any other prisoner.

And once he becomes a prisoner, Redford learns of the Colonel's harsh regime, one in which men are sometimes killed for stepping out of line.

At first Redford does not want to get involved, happier just serving his time and keeping himself to himself. Gradually he realises he cannot stand aside and brings his leadership qualities into play.

The plot develops into a battle of wills between the two men, the Colonel wanting to control his prisoners with an iron hand, the General commanding them with more psychological means.

It all boils up over the rebuilding of a historic wall within the prison gates. Redford is able to instil a sense of pride into the prisoners by getting them to build the wall properly while Gandolfini, realising he is losing control of the men, decides to knock it down.

Redford finally decides Gandolfini must go and the only way to remove him - according to the rule book - is by having Gandolfini lose control of his prison.

REDFORD sets about seizing control himself, explaining how the prison is designed like a castle and can be taken in the same way.

Redford does not appear in so many films these days so it is good to see him here in a role ideally suited to his stature - and age. He has a commanding dignity which brings a solid basis to his disgraced General and one can understand why men - even military prisoners - would want to follow him.

And he is matched by Gandolfini, his prison warden a nasty piece of work admittedly but given some understanding by the actor. The stand-offs between the two of them provide screen acting of the finest order.

It is also good to find an original screenplay for a change - story by David Scarpa (born on an army base), script by Scarpa and Graham Yost - and director Rod Lurie handles both the intimate drama and action scenes with skill.

If the prison siege has its unbelievable moments, including the creation of a mediaeval-style giant slingshot, it nevertheless provides a gripping and ultimately moving climax.