Encyclopedia Brown and the Case of the Two Spies - Donald J. Sobol

The famous boy detective solves ten, all new short mysteries. Readers can solve the mysteries along with him and find the answers in the back of the book. The young sneaker-clad super sleuth saves the day again in a collection of ten short mysteries that invite readers to puzzle out the solutions before consulting the answers in the back of the book. No mystery is too huge for Encyclopedia Brown, and there's no loengths that she won't go to crack the case