In the sixth book in the series, Johnny and Jerry reunite to solve the baffling mystery of a set of stagecoach robberies in which no robber ever showed up, but the lockbox was still somehow emptied during the stage run. Each boy has a life or death encounter with a pair of bad guys. There is an abundance of gadgets that play an important part in solving the case. Again, there is lots of good conversation, and enjoyable time on horseback and in the swimming hole. And, can you believe it, Johnny gets even more money forced on him! (Maybe the series should have been titled, "The Young Frontier Milionaire".)
