After successfully taking over the ship, Norman redirected it to Mudd to carry out "Lord" Mudd's plan, finally revealing his nature to James T. Kirk and Spock.
The plot ultimately failed. Captain Kirk and Spock correctly hypothesized that the android population was essentially a hive mind and that Norman was the central control locus. The androids were deactivated when Norman's processors were unable to deal with a flood of illogic presented to him by the Enterprise's crew.
The breakdown, however, was only temporary, as Norman returned to bid farewell to the Enterprise crew. (TOS: "I, Mudd")