Eli considers himself a mostly typical college student with one exception: he refuses to date. With plans of being ordained in his future, he doesn't want a relationship swaying his opinion one way or the other. Thanks to his strict religious upbringing, not even his friends question his decision. Until one night after too many shots celebrating with his best friend, he agrees to a marriage pact with someone he met that evening in the nightclub's bathroom.

Rhory, a charismatic and alluring over-sharer who never does anything but pursue pleasure, seems to be Eli's opposite in every way. Much to Eli's displeasure, Rhory refuses to disappear from Eli's life. Rhory much prefers spending the next decade pestering Eli with the countdown to his 35th birthday, when Eli promised himself to Rhory.

With the allure of the unobtainable only growing stronger in each of them, even Eli's religious calling won't deter Rhory's constant presence. Instead, the two cultivate a relationship that deepens with each passing year. Even when Eli and Rhory find themselves enmeshed with each other, one problem remains: Rhory is a demon, who will devour anyone who breaks a promise to him.