Unlike most of the "giant bugs" sci-fi programmers of the 1950s, which are good for little more than a campy laugh today, Them! remains a compelling and entertaining thriller with an unusually intelligent script, strong performances from a fine cast, and tense, well-paced direction that knows how to play this material seriously. While the special effects technology is not especially impressive by today's standards, watch Them! after such anti-classics as Beginning of the End or Earth vs. the Spider and you'll realize how striking this film's giant ants must have looked in 1954. More important, Them! generates a palpable tension from the start, never overplaying its hand as it gradually develops the unreality of the mutated insects, well after establishing that a real and deadly menace is terrorizing the desert. James Arness and James Whitmore are capable and credible lawmen, Edmund Gwenn keeps his "lovable" eccentricities to a minimum as Dr. Medford, and the charming but all-business Joan Weldon lifts her character above the usual sci-fi token woman. Fess Parker and Dub Taylor make the most of their bit parts, and, if you keep an eye peeled, you'll notice Leonard Nimoy using the teletype machine. Them! blends the lean and efficient construction of a B-picture with the craft that studios usually reserved for more expensive efforts, and the result is one of the best sci-fi films of its era.