Young Frank is an architect. He lives with his grandfather, Old Frank, who is also an architect and his spotted dog, Eddie. Using anything he can get his hands on; macaroni, pillows, toilet paper, shoes Young Frank likes to build buildings that twist, chairs with zig zag legs and even entire cities. But Old Frank disapproves, saying architects only build buildings. One day they go to visit The Museum of Modern Art in New York City. There, they see work by two famous architects named Frank: Frank Gehry's cardboard wiggly chair and Frank Lloyd Wright's Broadacre City, among other things. Old Frank sees that architects can do more than he thought they could. Together, Old Frank and Young Frank go home and build buildings of every shape and size, "tall ones, squat ones, tubular ones and just plain weird ones," using any material they find, even cookies! At the end of the day, when they go to bed, Young Frank feels a little older, and Old Frank feels a little younger and a little wiser.