French Kiss by Eric Van Lustbader

The murderous search for the Prey Dauw is on–the trio of weapons so imbued with mythic power that it is said whoever possesses them can dominate Indochina and control its opium. Two men have aleady been murdered for the Pray Duaw, and now their brothers, New York lawyer, Chris Haye, and NYPD detective Steve Guarda, are ready to face the savage madman who will stop at nothing to destroy them.