Jimmy the Kid by Donald E. Westlake

Here's the five-member Dortmunder Gang trying to achieve the perfect crime by following a paperback novel. They intend to follow the book's blueprint for a child heist in order to succeed at last at something crooked. But, they never counted on this 12-year-old kid!

Do it by the book
just stick to the script, Jimmy
no need to show off.

This is the least good Dortmunder novel in the series so far. The characters are getting stale — Rollo always describes people by what they drink, Murch only talks about what routes he drives, etc — but it's fun enough. A problem with so many books with a “twist” is that they try to subtly point out to you that there will be a twist, without explicitly saying what. But there is only ever one possible twist, and so knowing there will be one is sufficient to learn what it is. Jimmy the Kid falls to this problem, which makes the third act predictable and rather boring. All in all, it's a fine read, but I wouldn't have picked it up if it were a standalone novel.