Professor Nimnul has invented a device to transmit himself across telephone wires, and uses it to steal scientific devices from guarded laboratories. A neglected Zipper discovers Nimnul in the act and is caught in the Modemizer with him, leading to two creatures out of The Fly.
- Gregg Berger as Male Guard, Doctor, Police Operator, Man in Window, Squad Commander, Man at Restaurant, Dispatcher
- Susan Blu as Female Guard, News Reporter, Scared Woman, Teenage Girl
- Corey Burton as Dale, Zipper, Kid in Window, Kids at Park
- Peter Cullen as Officer Kirby, Officer Muldoon
- Jim Cummings as Monterey Jack, Professor Norton Nimnul, Waiter
- Tress MacNeille as Chip, Gadget Hackwrench, Radio Voice
- Fran Ryan as Teacher
- Final appearance of Officer Kirby and Officer Muldoon.
- It is also the final episode where Peter Cullen is credited with a role.