When your average, run-of-the-mill retired superhero Latin teacher meets an angel on the underground, it's not only runaway trains that spark.

Christian Winter used to save the world. In World War II, when good and bad was a simple matter of whose side you were on, life seemed so much simpler. Back then it was easy for a superman to see the troops safely home. Back then it was easy to be Mithras.

Long since retired to teach Latin in a London school, the man who used to be Mithras wants nothing more than a cup of tea and a quiet life. All that changes thanks to a runaway train on the Northern Line, and a red-headed Scottish angel whose eyes are bluer than a summer sky, who just happens to have a thing for chaps in tweed.

Christian is swept along by Freddy Rose's passion and enthusiasm, and his efforts to resist the Scottish angel's attractions aren't exactly heartfelt, but can the passionate angel and an encounter with a very important lady tempt Mithras back to a life of adventure?