The supersub Seaview in the Arctic, is pummeled underwater by falling iceburg sections. Admiral Nelson (Walter Pigeon)& Capt Crane (Robert Sterling) discover the sky in flames, & learn the Van Allen radiation belt has caught fire. Before heading to a UN conference, they pick up a lone scientist, Alvarez (Michael Ansara). Watching for crew stress is civilian psychologist Dr Hillery (Joan Fontaine). At the UN, Adm Nelson & Commodore Emery's (Peter Lorre) plan to save the earth is rejected. The Seaview encounters a mine field, giant squid & persuing subs, head to the Pacific, to fire a special missle. Alvarez & Hilliard each have separate ideas to stop Adm Nelson & his plan.