Perilous Games by J. M. Brister

Gray Tower, Incorporated: A private military company run by billionaire Miles Bryant. Their gray ops missions are executed by the best of the best, including ex-military, special forces, and the exceptionally talented.
Ashlen Cole is unwittingly put at risk by her uncle’s shady dealings. Protected by her hunky bodyguard, she may have a fighting chance. When her ex-fiancé shows up to save the day, he accidentally puts her in grave danger.
Mercer Cade may be elite, but he struggles physically and emotionally. Though he is placed on a seemingly easy bodyguard mission, he must ignore his feelings for the beautiful woman he’s sworn to protect. When law enforcement clashes with Gray Tower, the mission is put in jeopardy.