Moriarty and his gang manage to steal a shipment of gold, but Inspector Lestrade's investigation is making it difficult for the gang to get the gold out of London. Meanwhile, Hound and Watson investigates an odd break-in and robbery at a company making a new blimp.

Moriarty enters a prestigious airplane race, with the intent of sabotaging his way into first place, including stealing parts from other entrants to make his plane the best. Mrs. Hudson, Hound and Watson enter the race in hopes of stopping him.