The Book of Mormon at the Prince of Wales Theatre was unexpectedly good

The obvious reason for seeing The Book of Mormon is that is comes from the creative team that brought us the deeply irreverent and funny South Park. The second reason was an offer through work.

I booked the tickets some time ago before the show opened and since then it has become a large hit, which I had not expected as South Park's appeal is definitely fringe rather than mainstream.

I took my seat in the third row of the stalls with some excitement and anticipation.

The show starts much as you would expect by poking fun at the large dollops of faith required to believe the origins of Mormonism. Fun is also poked at the Elders who are trained to go out and spread the word.

We follow two of these who are sent to Uganda. One is the star of the training group, a typical all-American kid, and the other is a dumpy friendless geek. Their mission gets off to a bad start when they learn that the locals chant the equivalent of "Fuck You God" when they are upset. Things then get worse when they meet their colleagues who have all sorts of personal issues, as this overtly gay dance suggests.

The Mormons had failed to convert anybody until the geeky Elder Cunningham mixes The Book of Mormon with some themes from his favourite sci-fi films and shows. These new stories, even weirder than the originals, capture the natives' imagination.

There are complications, of course, such as the local war lord and the regional Mormon management, and a whole heap of minor things like the doctor who keeps reminding us that he has maggots in his scrotum.

What surprised me, looking beyond the earthy humour, was how good a musical it was.

The songs were clever and full of unpredictable lyrics; so unlike Les Miserables. The songs had good tunes too and were not just simple vessels to carry the words. The story was engaging and had a lot of warmth in it when it could have just been cynical. Less unexpected, because South Park does it too, was the successful use of a wide range of characters.

The Book of Mormon really is a good show and it is easy to see why it is sold out for months to come.