It was supposed to be a fun spring break trip - in 1989, Mark Kilroy and his friends from college went to South Padre Island, Texas, to party and have fun. During a short trip across the border into Mexico one night, Mark got separated from his friends - and was never seen alive again. His family and friends suffered an excruciating 4-week search for Mark, until his body was found on a Mexican ranch - along with evidence of a cult that practiced human sacrifice.