Sand Trap (1998)

After falling victim to a burglar, Nelson, a wealthy businessman, takes a trip to the desert with his wife Margo and lawyer/friend Jack. The trip takes an unexpected turn when Jack helps Nelson over a cliff. Jack and Margo return to the site with the sheriff only to discover Nelson's body is missing, indicating he is still alive. As Nelson struggles to survive against madness and the elements, two separate searches for him are conducted--one by an increasingly suspicious sheriff and the other by the treacherous Margo and Jack.