Late one night, three otherworldly creatures appear and sweep Meg Murry, her brother Charles Wallace, and their friend Calvin O'Keefe away on a mission to save Mr. Murray, who has gone missing while doing top-secret work for the government. They travel via tesseract--a wrinkle that transports one across space and time--to the planet Camazotz, where Mr. Murray is being held captive. There they discover a dark force that threatens not only Mr. Murray but the safety of the whole universe.