Jill McTeague is your average high school girl. With the help of her best friends Ramie and Daria, she embarks on a mission to be Tommy Knutson's prom date. As she becomes more involved with Tommy, he opens up to her with a secret similar to her own. Can she tell him why she is really gone for four days each month, something she won't even tell Ramie?

Meet Jack - he lives for four days every month. Jill physically and emotionally transforms Jack, anatomy and all, and for the last few years he has been content with spending those days locked in solitude in Jill's room daydreaming of Ramie. Anti-Jack Mrs. McTeague keeps his needs satisfied with food and pornography, while Mr. McTeague has confined himself to the basement to meditate and practice yoga.

But Jack's contentment has reached its end. If life wasn't hard enough having such a secret, Jill must resist harder to keep him one as he fights to be known and released from his captivity.