Cat, Krissie, Marcos and Tommy are marooned on an island when their boat floats free from its anchorage. While Mike and Ashley search for them when they fail to report back to work, the foursome's situation becomes desperate when Krissie is bitten by a poisonous spider and a crazed ex-Vietnam soldier hiding on the island thinks Tommy is the man responsible for the loss of the old soldier's platoon twenty-five years earlier.