In the 1580s, the Sea Hawks -- the name given to the bold privateers who prowl the oceans taking ships and treasure on behalf the British crown -- are the most dedicated defenders of British interests in the face of the expanding power of Philip of Spain. And Captain Geoffrey Thorpe (Errol Flynn) is the boldest of the Sea Hawks, responsible for capturing and destroying more than 50 Spanish ships and ten Spanish cities. His capture of a Spanish galleon, however, leads to more than he bargained for, in a romance with the ambassador's niece (Brenda Marshall) and the first whiff of a plan to put Spanish spies into the court of Elizabeth I (Flora Robson). Thorpe's boldness leads him to a daring raid on a treasure caravan in Panama which, thanks to treachery within Elizabeth's court, gets him captured and, with his crew, sentenced to the life of a slave aboard a Spanish ship. Meanwhile, Philip of Spain decides to wipe the threat posed by Elizabeth's independence from the sea by conquering the island nation with his armada. Thorpe, though chained to an oar, knows who the traitor at court is and plans to expose him and Philip's plans, but can he and his men break their bonds and get back to England alive in time to thwart the plans for conquest?
The Sea Hawk was the last and most mature of Flynn's swashbuckling adventure films, played with brilliant stylistic flourishes by the star at his most charismatic, and most serious and studied when working with Flora Robson, whom he apparently genuinely respected. Boasting the handsomest, most opulent production values of a Warner Bros. period film to date, The Sea Hawk was made possible in part by a huge new floodable soundstage. Another highlight was the best adventure film score ever written by Erich Wolfgang Korngold; and the script's seriousness was nailed down by various not-so-veiled references not to 16th century Spain but 20th century Nazi Germany. The movie was cut by over 20 minutes for a reissue with The Sea Wolf, and the complete version was lost until a preservation-quality source was found at the British Film Institute. Since then, that 128-minute version -- which actually contains a one-minute patriotic speech by Robson as Elizabeth that was originally left out of U.S. prints, as well as amber tinting in all of the Panamanian sequences -- has become standard.
~ Bruce Eder, All Movie Guide