Interesting little B-movie with laconic O'Neal an insurance investigator out to find why a wealthy shipping magnate is sinking his own vessels. Witty and literate, with some things to say about corporate power which are even more relevant today than when it was made. Makes a tonal shift from lighthearted spy stuff to serious revenge in the final reel; unfortunately that plot point is betrayed by the ridiculously revealing film poster. The murders show a definite Bava/giallo influence, somewhat surprising to see in an American film of this vintage.
Note: IMDb says Cynthia Baxter's character is "Felice Valayan," but Gielgud introduces her as "Cynthia."