Hawksbill Station

In the mid-21st century, time travel is used to send political prisoners to Hawksbill Station, a prison camp in the late Cambrian Era. When the latest arrival suspiciously deflects questions about his crimes and knowledge of 'Up Front', the inmates decide to find out his secret. [NOTE: a novella length version of this story is also available.] Hugo Award Nominee, Nebula Award. Nominee