Secret Agent Jack Stalwart by Elizabeth Singer Hunt

Secret Agent Jack Stalwart : Paperback : Running Press,U.S. : 9781602860025 : 1602860025 : 04 Sep 2007 : Armed with a backpack loaded with ingenious gadgets (and his own common sense), Jack travels thorugh the world, hoping each mission will provide clues to his missing brothers whereabouts. In the meantime, Jack finds himself involved in a treasure hunt.