Our client, a set designer, inspired us to fill this Chelsea penthouse with surprises. We masked the entry closet behind panels designed to house a collection of heirloom Chinese screens. In the library, pivoting bookcases also hide a secret Murphy bed. The spiral stair is glowing glass, lit by a skylight above. We used a giant cube to separate and define the public rooms, then cut a fireplace into its rabbeted corner. Lastly, upstairs, a wall of fiber-optic tubes divides bedroom from bath.