Seventh Heaven by Kate Calloway

After a friend is brutually attacked, Cassidy James and one-time lover Erica Trinidad team up to find the assailant. Their investigation leads to the discovery of a gaming club which bets on people instead of cards. This time, the game is to find the famous lost treasure of Rainbow Ridge. James and Trinidad learn that members of the gaming club leave clues for unknowing victims of their schemes to discover. The two conceive a plan to beat the club members at their own game.