Both theater arts and the art of magic involve suspension of disbelief, but in different ways. We go to the theater to find truth while actors pretend to be people they're not; we go to a magic show to be fooled by real people pretending to do things that defy the laws of physics. When the two find common ground, it can work very well. Obscura is the third collaboration between magician Christian Cagigal and Exit Theatre to produce "strange little magic shows" — and it's turning into a sly San Francisco tradition. A one-man show in an intimate cafe, Obscura presents a collection of mildly creepy campfire tales and illustrates them through sleight of hand. The stories and tricks aren't all equally strong, but Cagigal is a charismatic storyteller and the show is nimble under his care. The set is surprisingly evocative for such a minimalist venue, and the use of a music box to segue between stories is inspired. It's not profound, it's not hilarious — but Obscura makes for a diverting evening.