Iowa farm fresh with Tom Greenfield who goes to spend a summer there with his grandmother and explore--from silo to fruit cellar to barn--as well as search for the missing emeralds via the map found on his uncle's person when he died. A gunshot, a prowler, a tornado provide a little background action for The Discovery--a dagger of archaeological import. . . . Wholesome at best, a nubbin for real young noggins.