Scoop, Muck and Liftie are all set to help Bob with the biggest job he's ever done: build a dam and turn an old quarry into a water reservoir for Spring City. Bob asks another builder, Conrad, to help clear the quarry with his Mega Machines. Conrad is secretly jealous that Bob has been awarded the contract to build the dam. He wants to undermine Bob's reputation, so he decides to sabotage the dam. Bob soon realizes that something is wrong… and now he and his team will have to do everything they can to save Spring City!
