James Garner plays an Army officer who puts his hobby to practical use in Tank. Zach (James Garner) moves to a new post in a backwoods Georgia town. Accompanying him is his family --his wife LaDonna (Shirley Jones) and his son Billy (C. Thomas Howell)-- and his prize recreational activity --a restored Sherman tank. Zach strolls into town one night and engages in conversation with Sarah (Jenilee Harrison), a 17-year-old prostitute, who works for the town crime czar and law enforcement authority, Sheriff Buelton (G.D. Spradlin). When one of Buelton's goons gets rough with Sarah, Zach slaps him down. In retaliation for Zach's infraction, Buelton arranges for Billy to be sent to a brutal prison farm on trumped-up drug charges. Zach tries to get Billy released, but to no avail. So he jumps on his trailer, starts up his Sherman tank and heads into town.