Episode 102 of "Without a Trace"
s05e08 Win Today

Though Jack's team thinks he's undercover at an illegal poker club frequented by the missing young man they are seeking, Jack is actually the hostage of a cold-blooded woman. After learning that Alex Stark, a missing 20-something man, lied to his girlfriend of three months about owning a cleaning service, the team wonders how he was living so luxuriously. They soon discover his ties to an illegal poker club and that he emptied his account of $48,000 three days prior to his disappearance. Jack goes undercover as a player at the club and, unbeknownst to his team, is soon at the mercy of Cynthia Neuwirth (Thompson), a dangerous acquaintance of Alex's who is convinced that Jack was hired to kill her.