The Keatons are surprised, but delighted, when Elyse's Aunt Rosemary shows up for a visit. Although Rosemary claims to have sent a letter and spoken with Mallory about her arrival, the mix-up is quickly forgotten as the family warmly welcomes their loving and favorite aunt. Rosemary charms the Keatons with her wit, humor and wonderful family stories. But soon, she begins to act strangely to simple questions, and Elyse starts to worry when Rosemary begins repeating things that have just been discussed. Finally, Rosemary admits that she has been having trouble with her memory and has no idea how she even got to the Keaton home.