One of a series of fiction for schools. The moral of this story, set in the 21st century, is that freedom has to be won and kept by the young.
It won the Guardian Prize for Children's Literature.
- Format: Hardback
- Pages: 160 pages
- Publisher: Pearson Education Limited
- Publication Date: 10/09/1973
- Category: Science fiction
- ISBN: 9780435121761