For six years Guerrin has become a werewolf, mindlessly killing every full moon. But one night he encounters Marya, and his urge to mate with her is so strong, he reverts to human form—thus beginning a magic spell that is his only hope of salvation.

If Guerrin and Marya can construct a collar of steel, silver and a ruby and fasten it about his neck at the moment he is both wolf and man, he will retain his own mind even in wolf shape. To complete the spell, each step must be accompanied by sex—a major distraction. Time is running out and if they fail to succeed by the time the moon rises on the third night, Guerrin will die.