Buck is hired by members of tontine to find out why so many of them are dying. The investigation takes Buck to Martinique and Belize. Eventually, Buck uncovers a deadly conspiracy that threatens all the members of the tontine.

• A financial scheme by which the subscribers to a loan or common fund receive each an annuity during his life, which increases as their number is diminished by death, till the last survivor enjoys the whole income; also applied to the share or right of each subscriber.—Oxford English Dictionary (online)

• I had learned about tontines and I thought one would be the perfect vehicle for a murder mystery.  However, since tontines are illegal in the United States, I had the sixteen people involved in the tontine go to Martinique, where, as a department (state) of the French Republic, tontines are legal.

• Members of the tontine are dying, so a legal representative for the remaining members, asks Buck to find out why they are dying and if the deaths are natural or forced.

• The plot takes him to Martinique and Belize and involves smugglers and money launderers.

• He discovers that a clever assassin is killing the members, but Buck never catches the killer.

• In Tontine, Buck and his beloved Cyndi Katz, a profiler, are on a hiatus from the relationship, so he is trying to date other women.

• He and Ruben are the founding partners of the agency (Jaspers & Marquez); Ruben is married with children, so Buck tries to protect him.

• Caridad Puente, a Santeria priestess, is their secretary.