High Adventure is the story of a bunch of shenanigans around a faked Mayan temple and smuggled Mayan antiquities all taking place in Belize. The main characters are a bush pilot who bought a useless piece of land, the scheming minister and developer who sold it to him, an idealistic archeology grad student, a gay couple of antique collectors, a nerdy midwestern museum curator and a mellow tribe of Mayan indians. Westlake wrote a few of these ensemble cast novels, ones that tend to have a bigger scale and don't fall into either any of his series or a specific genre (Humans and Kahawa are two other examples). I get the feeling that he vacationed in Belize and found it so fascinating that he decided to write a book about it. A big part of this book is about life in Belize and even a bit of history. He clearly has a lot of admiration for it and pits the way Belize accepted indigenous refugees from the other Central American countries (particularly Guatemala) against the miserable treatment they received from their own countries.
The story itself is a lot of fun. It has a good mix of characters and lots of very funny moments. The whole thing has a light, party vibe ("high" adventure), even though the climax involves a village getting attacked by a Guatemalan death squad. I quite enjoyed it and would recommend it if you are looking for some nice light escapist reading and want to learn a little bit about Belize. I have trouble believing things are quite as hunky-dory today as they were back then, considering the massive growth in the hardcore drug trade in the ensuing period. But it still sounds like it would be a cool place to visit.