While driving from Arizona to California with his act, the Atwood Orangutans (Cha Cha and Bobo), Tommy Atwood is run off the road. Tommy is knocked unconscious and Cha Cha and Bobo, frightened by the approaching police sirens, run away. Cha Cha is found by the Humane Society and later sent to a government research center in Washington, D.C.

Six weeks later, Cha Cha escapes from his cage and, while wandering about the building, enters a lab in which an enzyme designed to increase human intelligence is being developed. Cha Cha mixes some chemicals, drinks the result--and is suddenly endowed with the ability to talk. When tests reveal that he has an I.Q. of 256, he is named Mr. Smith and made a government consultant.

Tommy, later traced through Mr. Smith, is summoned to Washington and becomes Cha Cha's assistant. The series depicts the adventures of an articulate genius and government consultant--who happens to be an orangutan--as he attempts to become "human".