Cam, Lucca, Soledad: three ordinary people chosen by an alien power for reasons no one understands to undertake a journey no one on Earth could have imagined. They, and eighteen other young humans, have been sent by the alien Atoners to distant worlds to observe. To discover the Crime. To see with their own eyes the wrong done to humanity. At first everyone thought it was a joke. Then they thought it was some kind of viral marketing campaign. The ad had appeared on the Internet: "We are an alien race you may call the Atoners. Ten thousand years ago we wronged humanity profoundly. We cannot undo what has been done. But we wish humanity to understand it. Therefor ewe request twenty-one volunteers to visit seven planets to witness for us. We will convey each volunteer there and back in complete safety. Volunteers must speak English. Send requests for electronic applications to witness@atoners.com." A few days later, a huge new installation appeared on the mo