‘Lone Star’

“Lone Star” flashes back and forth between 1957 and today, and has a story complicated enough to demand complete attention. Investigating at skull that turns up in the desert is Sam Deeds (Chris Cooper), a second-generation sheriff recently returned to town. He also discovers that his old sweetheart (Elizabth Pena, picttred) is now divorced (Showtime Saturday at 8:30 p.m.).