In the far future, after human civilization has spread through the galaxy, communications begin to arrive in an apparently alien language. They appear to threaten invasion, but in order to counter the threat, the messages must first be understood.
- ISBN10 0575094206
- ISBN13 9780575094208
- Publish Date 29 March 2010 (first published 1 December 1975)
- Publish Status Active
- Publish Country GB
- Imprint Gollancz
- Format Paperback (B-Format (198x129 mm))
- Pages 208
- Language English