Caledonia @ King's Theatre

The National Theatre of Scotland's new play Caledonia is the story of the Darien debacle, Scotland’s idealistic seventeenth century venture to become a colonial power. The story centres on William Patterson, founder of the Bank of England, and one of the extraordinary financial heroes (or villains) Scotland has bequeathed the world from the sixteen hundreds onwards.

The play is neatly divided around the interval. The first half follows Patterson getting the scheme off the ground, the creation and journey of the fleet, and the first days in Darien. The second half follows the abandonment of the colony, Patterson's return to Scotland, and the political repercussions of the project's failure – judged by historians to be a significant influence in ratifying the Union with England.

The playwright, Alistair Beaton has a reputation as a satirist but the play is more a history play than a satire. There are welcome (indeed, required) potshots at greedy MPs and hubristic financiers - but what new play isn't going to include those? The scandals are not contemporary enough to scandalise, and the comedy is not the corruscating despair of timeless satire - the humour is genial rather than savage.

There are great strengths in the play - the first half imparts a real sense of the plasticity of history. You know that ultimately, the colony fails, but while watching Patterson's eloquence and drive you are swept away as much as his contemporaries. Was it such a foolish project? You start taking a historian's interest in understanding a different mindset and wondering whether New Edinburgh could have become the second home address of choice for wealthy bankers.

The first half has some cracking songs, and an amusing streak of bawdy throughout. Paul Higgins as Patterson and Frances Grey as Mrs Paterson inhabit their parts with humour and verve. (The play belongs to Patterson, and Higgins carries this off with aplomb.)

The second half drags a little. There's a lot of lamenting of lives lost to fever. Fair enough; but inevitably, this is a touch monotone. The first half of the play is solidly and entertainingly about money; the second half is about those who lost their lives to disease. This creates a rather broken-backed effect that dissipates  emotional involvement.

The production values and cast are as top-class as you would expect. In truth, rather in excess to requirements. The Pattersons are fully drawn and some characters sketched-in, but largely the cast play stock comedy characters - probably inevitably, given the play's broad canvas.

Ultimately, Caledonia presents Patterson as an enigma. This is appropriate for a play that focuses on a the complexities of a real historical figure rather than going for the black and white of satire.

More disappointingly for a contemporary play about finance, money too remains a mystery. The failure of the 'risk free investment' is well explained. But surely it’s not the failures of financial capitalism that are the surprise – what needs explaining is how it works so well. There are plenty of dramas that make you think you understand the spin and entanglements of quantum physics. Money must be more mysterious.