Having placed mines on the hull of a British warship whilst it is safe in harbour during the second World War , the two man crew of an Italian miniature submarine are captured and held prisoner whist the crew try and discover the nature of their mission!
John Mills
as Captain Morgan
Ettore Manni
as Luigi Durand de la Penne
Roberto Risso
as Emilio Bianchi
Robert Shaw
as Lieutenant Field
Liam Redmond
as Surgeon Commander Reilly
Dinsdale Landen
as Norris
John Meillon
as Bedford
Patrick Barr
as Rev. Ellis
Moray Watson
as Capt. Turnbull
Gordon Rollings
as Payne
Laurence Naismith
as Admiral
Leonardo Cortese
as Italian Commander
