Dennis

Neanderthals have developed a radically different civilization on a parallel Earth. A Neanderthal physicist, Ponter Boddit, accidentally passes from his universe into a Canadian underground research facility. Fortunately, a team of human scientists, including expert paleo-anthropologist Mary Vaughan, promptly identifies and warmly receives Ponter. Solving the language problem and much else is a mini-computer, called a Companion, implanted in the brain of every Neanderthal. But it can't help his fellow scientist back in his world, Adikor Huld, when the authorities charge Adikor with his murder.

A scientific experiment begins, and as the button is pressed, the unexpected occurs: everyone in the world goes to sleep for a few moments while everyone's consciousness is catapulted more than twenty years into the future. At the end of those moments, when the world reawakens, all human life is transformed by foreknowledge.