The Shepherd relates the story of a De Havilland Vampire pilot, going home on Christmas Eve 1957, whose aircraft suffers a complete electrical failure over the North Sea en route from Celle in northern Germany to RAF Lakenheath in Suffolk. Lost in fog and low on fuel, he is shepherded to a disused RAF dispersal field by the pilot of a De Havilland Mosquito fighter/bomber of World War II vintage, who has apparently been sent up to guide him in.
However, when he lands at the airfield - the fictional RAF Minton - he learns that his saviour was Johnny Kavanagh, a wartime RAF pilot who had been stationed at Minton and who had guided crippled bombers home; he disappeared over the North Sea in his Mosquito on his last mission, on Christmas Eve fourteen years before.