A new and unusual villain makes his presence known by stealing from the Batman: his Batmobile, Batarang, and Bat-Boat. Yet Batman cannot figure out WHY he would do such a thing.
When trying to stop the costumed criminal known as the Grasshopper from escaping with loot stolen from a bank, the crook tricks Batman and Robin into scaling the wall of a building, while he makes a quick getaway by stealing the Batmobile.
Later at an auction aboard a boat where Batman is to sell off one of his Batterangs for charity, it is stolen by the Grasshopper who manages to slip out of Batman's grasp. Batman call's Robin to come to his aid in the Batboat. However when Robin arrives, the Grasshopper steals the Batboat and kidnaps Robin, sending Batman back his Batterang with taunts about what he will steal next.
Deducing that the Grasshopper would be hiding out in the docks, Batman sees through their trap which uses a recording of Robin to call for help. Batman rounds up the crooks and turns them over to the police. On their way home in the Batmobile, they are startled by a recorded warning by a crook called the Outsider, who hired the Grasshopper to act on his behalf, he states that next time he will defeat them.