Alien jungle growth is spreading across Italy, and before long -- thanks to a crewman who is really an alien spy -- the vegetation invades Seaview too. The Admiral has built a device that might help, but first he and Crane have to fight their way through the overgrown corridors to prevent the missiles being used to spread the infestation even farther. * Patrick Culliton played various crewmen over Voyage's 4 seasons.
Elenco: Richard Basehart , David Hedison , Robert Duvall , Terry Becker , Del Monroe , Paul Trinka , Richard Bull , Robert Dowdell .