Ensemble cast of off-the-wall Warner Brothers characters, appearing in a wide variety of roles. Wakko, Yakko, and Dot Warner, are WB Studio creations who were just too "zany" to be of any use to the studio. Pinky and the Brain are two mice bent on world domination. Rita and Runt are a cat and dog team, who get into perilous situations every episode, put always seem to find time to sing a song. Bobby, Pesto, and Squit are the Goodfeathers, part of a New York mob of pigeons, who worship Martin Scorsese. Slappy the Squirrel is a late middle-age squirrel; she starred in a series of popular cartoons in the Golden Age. Buttons is a watch-dog, charged with watching the mischievous toddler, Mindy. Chicken Boo is a giant chicken trying to integrate into human society. Flavio and Marita are two urbane hippopotami.

提姆（杰夫丹尼尔 饰演）是个很有企图心的电视新闻记者，可是他却得不到老板的赏识，某次回家的路上，竟遇上火星人的太空船撞上地球！转化地球人外观的火星人马汀，为了修复太空船，只好找上提姆，提姆与马汀相处越久，越发觉它其实是个善良的外星人，但因为马汀的行为怪异，不知不觉被太空研究中心小组成员盯上了……