Animated adventure comedy. When the Justice League disappear, Lois Lane and Jimmy Olson investigate the Hall of Justice but are chased out by a phantom that prompts them to call Mystery Inc. for help - while on their way to Metropolis, the gang discover that the city has been overrun by super-villains as a result of the League's absence. After meeting Lex Luthor, Mercy Graves, and Luthor's dog Rex, can Krypto the Superdog help Mystery Inc. find out what happened to the Justice League?