ALL SIGNS POINT to the strong probability that somewhere in Merrie Old England, someone, for some purpose unknown (but certainly criminal) is building himself an atom bomb!
Obviously, it's a situation that requires the immediate attention of the AVENGERS — John Steed and Tara King — and they promptly swing into action.
The two search everywhere for clues — from jewelers' shops to a gypsy encampment — at one point the elegant Steed even descends from his stately Bentley to career about the countryside all day on a bicycle!
Time is running out. CAN THE AVENGERS FIND THIS MANIAC BEFORE HE OR SHE BLOWS UP HALF OF ENGLAND?