Kassie (Jennifer Aniston) is a smart, fun-loving single woman who, despite her neurotic best friend Wally's (Jason Bateman) objections, decides it's time to have a baby - even if it means doing it by herself! Kassie gets her wish with a little help from a charming sperm donor (Patrick Wilson) but unbeknownst to her, a mishap at the insemination party means Wally drunkenly switched the donation with his own 'special offering' then promptly forgot about it... That is until seven years later when Wally finally gets acquainted with Kassie's son Sebastian, whose precocity, neuroses and hypochondria bear a striking similarity to his own characteristics. Could it be... ?!