When Krista needs Ariel's biochemical expertise because her new boyfriend can turn into a mountain lion, Ariel thinks her sister has lost her mind. But the possibility of a major discovery like this is too much of a temptation to ignore. Create a drug to stop a shifter from forcing a mating? Only if she got to test his sexual limits herself. Rob thinks Ariel is an angel in disguise, and he immediately knows she's the one for him. But is he strong enough to resist his animal's need to claim her once the temptation begins?