Henry and Muriel Rush are the owners of a duplex in San Francisco, where they live with their two adult daughters: 21-year-old banker Jackie and 18-year-old college freshman Sara, in a cramped, awkward arrangement. Henry is a cartoonist of a comic strip called Cosmic Cow, while Muriel is a former musician currently working as a photographer. When Henry and Muriel's downstairs tenant, Myron Rafkin, suddenly dies, the family discovers Rafkin was living a secret life as a transvestite, and the many mysterious women Henry had been opening the door for all those years were actually Rafkin himself. Sara comes up with the idea for her and Jackie to convince their parents to let them to move into Rafkin's former apartment. Henry rejects the idea at first, but after Henry interviews a couple of prospective tenants he doesn't approve of, Muriel convinces him that having the girls move in may not be such a bad idea.

With Sara and Jackie living downstairs, Henry has become a snoop-aholic. Sara asks for permission to go to Lake Tahoe for the weekend, leaving behind birth control pills that Henry assumes is hers and Jackie lets her navy boyfriend spend the night, causing Henry to hit the roof.

Jackie, who works at a bank, tries to make a money delivery to a supermarket, but finds it closed. After calling her boss, she finds herself in charge of a bag with $100,000 in it. Meanwhile, Muriel and Henry are convinced that the ex-convict plumbers are going to rip them off, but soon Jackie's bag of money enters the fray.

Sara befriends Monroe Ficus, a recently dumped young man, who quickly follows her all over the place even following her home. Meanwhile, Henry and Muriel plan on celebrating their anniversary but just before heading out for the evening they get a phone call from Sara and Monroe with news that they have been arrested.

Jackie and Sara have split the cost of rent but when Sara is unable to pay her half, Henry tells her to go out and get a job. Sara easily gets a job as a waitress, but Henry is in no way thrilled with the skimpy costume that she has to wear. This leads to a blow up between Henry and Muriel leading her to move in with Jackie and Sara.