A JIB DOOR, that is, one sans visible jambs and camouflaged with the same decoration that surrounds it, disappears into the wall. Cue the pivoting shelves that open at the sound of a pattern of notes on Bruce Wayne’s piano in “Batman Begins” or Harry Potter’s sad closet-room concealed behind paneling under the dreadful Dursley’s stairs, virtually unnoticeable but for the slide-bolt latch.

Beyond their inherent mystery, however, jib doors appeal to interior designers for various reasons. “Secret doors are super chic and surprising but also practical,” said Charlotte Barnes, a Greenwich, Conn., pro who simplified the architecture of a family room by continuing the paisley-patterned wallcovering across two flush doors. These nearly invisible doors are ideal for establishing symmetry, for example, in an oddly apertured room, she said, “or to play down a hallway full of closets, so your eye flows along without interruption.” Jib doors have other advantages but also some challenges. Here, a guide.