Mystery of the Roman ransom

[intro]In these two delightful history-mysteries, seven boys in Ancient Rome solve strange crimes . . . thanks to some help from their cranky teacher, a little bit of logic, and a lot of amusing misadventure.

It seems the boys can get nothing right: Their teacher's fiftieth birthday islongpast (they should have done their math homework); the servant they bought as a present for his birthday isn't just your run-of-the-mill Gaul slave but a courier running for his life; and, to top it all off, the message he's carrying requests the assassination of a Roman senator--the father of one of the boys.