Episode 1 - The Eternity Ring　　MI5 suspects British atomic research has been infiltrated, and ask Foyle to investigate whether a Russian spy network could be at work in the heart of London.　　Episode 2 - The Cage　　Foyle’s investigation into the death of a nameless Russian leads to a mysterious military facility and the discovery that the victim was a spy with dangerous connections to British intelligence.　　Episode 3 - Sunflower　　Professor Peter Van Haren gives a lecture to a group of students on the self-portraits of the artist Rembrandt and causes a young man to suffer a frightening flashback which ends in tragedy.