Episode 85 of "Without a Trace"
s04e15 The Stranger

While investigating the disappearance of a suburban stay-at-home mother, the team begins to suspect that she may not be as innocent as her husband and minister think she is. Leah Robinson was last seen leaving a Manhattan gallery opening party with a man who was arguing with her. When her husband, Ken, is stumped as to the man's identity and Leah's reason for being at the event, the team explores whether her disappearance could be linked to an affair gone awry. The investigation takes an unexpected turn when the agents learn that Leah secretly followed her husband on his recent "hunting trip" and saw him with a waitress who was fatally shot days later. Meanwhile, when their departments converge to work on this case, Jack and Anne butt heads on how to best conduct the investigation.