Cliff Robertson and George Chakiris star in this dumbed-down version of The Guns of Navarone. During World War II, the story concerns a Scandinavian underground leader, Erik Bergman (George Chakiris), who reports to British authorities the location of a German V2 fuel plant. As is the case in most World War II action films, the plant is in an impregnable location -- beneath an overhanging cliff at the end of a highly defended fjord. The only way the British can hope to destroy the plant is by collapsing the cliff on top of it. In order to do that, light Mosquito aircraft must be utilized. This is the job assigned to Wing Commander Roy Grant's (Cliff Robertson) 633 Squadron. In order to assist Grant in his air attack, Bergman attempts a simultaneous ground attack, but the ground attack fails, and Bergman is captured by the Germans. When he is tortured in their efforts to uncover the RAF plans, Bergman may not be able to withhold the top-secret information. Howard Koch and James Clavell adapted their screenplay from Frederick E. Smith's novel, reportedly based on a true story. Though Koch and Clavell are each known for their excellent writing, Squadron 633 is notable mostly for its adept cinematography from the co-operative effort of John Wilcox and Edward Scaife.
~ Paul Brenner, All Movie Guide