Revenge is sometimes very sweet. In the 1975 thriller "The Human Factor," George Kennedy plays John Kinsdale, a devout family man working as a NATO computer specialist in Naples, Italy. When political terrorists kill his entire family, John uses his technological prowess to track and hunt down the cold-blooded killers. Trying to prevent him from taking the law into his own hands are a local police inspector, a U.S. military commander and his friend Mike MacAllister, played by Sir John Mills. But nothingcan prevent John from meting out his bloody brand of grief-stricken revenge in this taut tale.