West and Gordon are assigned to protect Dr. Raven, inventor of an important new weapon. They soon discover that Raven is a member of a tontine - an investment group operating on the law of survival. A meeting of the tontine's members is imminent and several attempts are made on Raven's life as they travel to it; additionally, the agents learn that three other members of the group are already dead. They arrive at the meeting with the body count still rising and find themselves trapped in their host's house with a mysterious killer.
Tropes present in this episode:
- Backwards-Firing Gun: Used in one of the murders. It's substituted for the member's own weapon - a particularly trigger-happy member, by no coincidence.
- Closed Circle: The only door out of the Old Dark House is jammed shut, trapping Jim, Artie, and the victims-to-be within.
- Complexity Addiction: The murderer suffers from it; his schemes for murder keep getting more and more elaborate.
- Nasty Party: The shareholder's retreat. A bunch of not especially nice people who don't much care for each other trapped in a large house on a stormy night - and slowly being killed off one by one.
- Old Dark House: Martin Grevely, one of the tontine's members, hosts the group at his very large, not particularly pleasant mansion.
- Ten Little Murder Victims: The remaining members of the tontine at Grevely's house. In this case there's not only a mole but an identical twin involved.
- Tontine: West and Gordon are assigned to protect a government scientist invested in a tontine whose members are being killed off.