His concerns deepen as Matthew becomes increasingly distressed and blames it on arguments with this unseen companion, whom he calls "Chocky".

As the story unfolds it becomes clear that the friend is far from imaginary but is an alien consciousness communicating with Matthew's mind.

The cast includes: BBC Radio 4 presented a reading by Andrew Burt of the novel in seven 15-minute episodes, abridged by Neville Teller, produced by David Johnson, and broadcast daily between 19 and 27 May 1975.

An adaptation by John Constable as a single 90-minute drama for BBC Radio 4, directed by Melanie Harris, was first broadcast on 18 March 1998.

The 3rd series, Chocky's Challenge, was released on 23 August 2010 Steven Spielberg acquired film rights in September 2008 and said he was interested in directing.