The Cipher by Kathe Koja

Pure black and the sense of pulsation, especially when you look at it too closely, the sense of something not living but alive." When a strange hole materializes in a storage room, would-be poet Nicholas and his feral lover Nakota allow their curiosity to lead them into the depths of terror. "Wouldn't it be wild to go down there?" says Nakota. Nicholas says, "We're not." But no one is in control, and their experiments lead to obsession, violence, and a very final transformation for everyone who gets too close to the Funhole.