The secretary of these flats, even the hall porter, should have a master key.
They then broke the seal and entered the room by means of a master key.
Look, only look into the closet; wait here a moment, and I'll fetch a master key that shall open every one of them.
He decided to say nothing about the Demon or the accidental striking of the master key.
Pausing at a door, the cleaning woman fitted a master key into the lock.
When Raines came in he inserted the master key in the lock and opened the deposit box.
Why, oh why did not some intelligent person strike the master key!
The theory of the class struggle is the master key to the bewilderments and confusions of history.
And as she looked at Harry, it was as if some key, some master key, were suddenly and noiselessly turned in the lock.
To all this problem, vexing so many generations, the clear and witting touch of Lincoln's sacrificial penitence is the master key.