Detective drama Endeavour, the prequel to Inspector Morse, is set for a fourth series - and it will pay homage to Morse's 30th anniversary.
Endeavour stars Shaun Evans as the young Morse, with the story picking up where series three left off in the summer of 1967.
2017 marks the 30th anniversary of Inspector Morse, which ran from 1987 to 2000, and programme makers have promised "many respectful tips of the trilby from Endeavour to its much admired progenitor in terms of guest casting, heritage characters and stories".
The fourth series, written once again by Inspector Morse screenwriter Russell Lewis and filmed in Oxford, will see the return of Roger Allam as Endeavour's senior officer Detective Inspector Fred Thursday.
Anton Lesser will return as Chief Superintendent Reginald Bright, Sean Rigby as PC Jim Strange, James Bradshaw as Doctor Max deBryn, Caroline O'Neil as Win Thursday, Dakota Blue Richards as WPC Shirley Trewlove, and Abigail Thaw as Dorothea Frazil.
With series four starting barely a fortnight since we last met the characters, we find them picking up the pieces of their lives.
Endeavour waits to hear the result of his Sergeant's Exam and nurses his heartache, while Thursday and Win deal with their own grief - an empty home, Sam gone to the army and Joan who-knows-where.
The summer of 1967 will take a turn for the dramatic as, in Lovelace College, a "thinking machine" has been developed to challenge the Soviets as Endeavour is drawn into Cold War intrigue.
Programme makers have teased that the story will feature "an immortal game that will cast the life of a friend into the hazard".