A TREE HOUSE at night is the setting for this exciting, modern mystery. It is about two boys who decide to build a house up in a tree so that they can observe the night life of animals and birds and get to know more about them. One of the boys is from the city and is afraid of the dark, although he doesn't admit it. This gives added interest to the building of the house and the nights that the boys spend there after it is constructed. Each night is more exciting than the last and there is a mystery to be solved as well as many interesting creatures to observe.

This is a typical Mary Adrian mystery for boys and girls. It is full of action and suspense, and has an added dividend in the nature lore that the reader picks up as he follows the exciting events of the story.

The book has a factual addendum which shows how youngsters can make a nature log of their own like the one the boys keep in the story.

From the dust jacket