The Red Bend Bank Robbery — David Drake (1)

The second book in the Doc and Johnny's Old West Mystery series. A carnival and rodeo run by Gypsies come to Red Bend and Johnny becomes friends with an orphan boy traveling with them. Johnny and Doc find they have two mysteries to solve: First, finding the boy's mother for him and trying to get them back together. Second, figuring out how a bank can be robbed when nobody enters the bank and yet all the money has somehow been taken. (Third, of course is who robbed the bank.) Johnny solves all three along with running a fake tonic salesman out of town, entering an important horse race with Diablo (his horse), and spending time with his special girlfriend.