Whiz Tanner and the Uncommitted Crime

Whiz and Joey witness an apparent breaking and entering. They instantly assume the roles of Agent M and Agent K of the Tanner-Dent Detective Agency. The victim doesn't want them investigating, which makes them more curious. They uncover spies, secret identities and the plans for a terrible crime. But nothing is as it appears as they ride for their lives up roads, through woods and cow pastures, until they find themselves on a wobbly swinging bridge. How do all their clues fit together? Can Whiz (uh, I mean, Agent M) find the the connection?