A young boy lets the animals out of their cages at the Zoo, to set them free, but the animals start taking over the town.

Jay North
as Chris Carlyle

Martin Milner
as Dr. Del Hartwood

Andy Devine
as Branch Hawksbill

Joyce Meadows
as Isobel Moon

Jim Davis
as Adam Carlyle

Dorothy Green
as Anne Carlyle

Karen Green
as Wilma Carlyle

Vaughn Taylor
as Councilman Pew

Wayne Thomas
as Newscaster

Eddie Quillan
as Man Watching TV