World's Finest, Part 1.The Joker steals a large piece of Kryptonite and then comes to Metropolis, offering to kill Superman for Lex Luthor in exchange for one billion American dollars. Meanwhile, Bruce Wayne pays a visit to Metropolis to negotiate a business deal with Lex. Bruce also uses this opportunity to suit up as Batman and hunt the clown. Superman uses his X-ray vision to discover Batman's identity while Batman uses a tracking device on Superman's cape to discover his.