Northwest Passage: S1 Ep 17 The Secret Cliff (1959)

Keith Larsen, Buddy Ebsen, Don Burnett
George Waggner
The French capture a British spy and are convinced that he has discovered a route to climb the 200 foot cliffs that protect the city from the St. Lawrence River below. The British army sends Rogers with a beautiful double-agent to Quebec to try to learn about the route from the spy who is imprisoned in the city's deepest dungeon. (BW)