The 300 Spartans is an account of the 480 B.C. Battle of Thermopylae, in which the Greek Spartan King Leonidis, played by Richard Egan, led a remarkably small number of Greek Sparta to victory over an invading Persian army led by evil King Xerxes that was thought to number over 25,000. This spectacular conflict gave the Grecians enough time to organize a force to ultimately repel the Persians, and thus change the course of Western civilization.

Belgian nun Sister Ann is sent to another order where she's at first committed to helping troubled souls, like Nichole and little Dominic. When Father Clementi hears Sister Ann's uplifting singing style, he takes her to a talent contest. Sister Ann is signed to a record deal and everyone is listening to her lighthearted songs. She is unprepared for her newfound fame (like appearing on The Ed Sullivan Show) and unwanted side effects, including a wrongful attraction to an old friend.

Near the end of the war in Germany, GI Steve Boland, a self-described "sharp-operator", meets a German girl, Ilsa, and they fall in love. Ilsa's brother Karl, whom she has not seen in three years, and his fellow Nazi Ludwig visit Ilsa. Karl proudly informs her that he and Ludwig are "Werewolves", a group of Nazi assassins parachuted behind Allied lines for the purpose of killing Allied High Command officers. She and Steve go to Army Intelligence with their information, where Steve is immediately arrested for being A.W.O.L. Captain Melton of Army G-2 intervenes on Steve's behalf, as G-2 has had a suspicion about the existence of the "Werewolves" but no concrete info before now.

Four sisters in New Zealand fall for soldiers en route to the Pacific theater in WWII.