Father Unwin and Matthew are put on the case when enemy spy George Grey escapes from a maximum security prison and disappears over the estate of Sir Humphrey Barton.
When Father Unwin is taken ill, he has an extraordinary dream. Can he and Matthew survive their dangerous journey in Gabriel, the flying car, and deliver medical supplies to plague-ridden Africa?
Father Unwin encounters trouble in his parish when a local scientist is held hostage and forced to complete work on a prototype ultrasonic rifle so that mercenaries can shoot down a new jet.
Father Unwin visits a health farm in order to keep tabs on one of the residents, a notorious spy named Sakov, and is baffled when Sakov manages to engineer the crash of a test car whilst secured in a treatment room.
Father Unwin is assigned to protect the King of Muldovia from his brother's assassination attempts. When the flight crew of their plane is incapacitated, Father Unwin ends up having to pilot the plane himself!
