Ken Wilburforce is building a robot he has named Metal Mickey. It becomes sentient when girl next door Janey feeds it a Galactic Fizzbomb. Now all Ken and his siblings have to do is to convince their dad that Mickey can be useful around the house so he will let them keep him.
Burglars Jonathan and Harry break into the Wilburforce home and decide to kidnap Metal Mickey and hold him for ransom. However, Mr. W. has no intention of paying. Not even when Granny stumbles upon the burglar's hiding place and gets kidnapped as well.
Two government inspectors visit the Wilberforce home demanding a look at Metal Mickey. The children's attempt to make Mickey appear to be a harmless toy fails and the inspectors decide to take away Mickey so he can be examined in pieces.
Mickey discovers he can make music and becomes a pop star thanks to a song written by Haley & Janey and some shady managing courtesy of Mr. Jason. Before long the Metal superstar leaves the Wilburforce family behind and moves into his own flat.