Episode 1 - Eternal Ring MI5 suspects that Britain's atomic research has been infiltrated and asks Foyle to investigate whether a Russian spy network may be working in the heart of London. Episode 2 - Cage Foyle's investigation into the death of an unnamed Russian leads him to a mysterious military facility and discovers that the victim is a spy with dangerous ties to British intelligence. Episode 3 - Sunflowers Professor Peter Van Haaren teaches a group of students about the artist Rembrandt's Self-Portrait, causing a young man to suffer a terrifying flashback and ending in tragedy.