Doc Empty Apartment

Halting the others with an uplifted arm, some yards from the door, Doc advanced alone. He did not want them near enough that the sound of their breathing would interfere with his listening. For Doc's ears were keen enough that he could detect the faintest respiration noises of men within the apartment.

He listened. Lowering close to the threshold, where there gaped a small crack, he used his nostrils. The olfactory senses of the average man are underdeveloped through insufficient use. He has no need for a super-keen organ of smell. Indeed, city life is more comfortable if the multitude of odors present go unnoticed. But Doc Savage, through unremitting, scientific exercise, had developed an olfactory sense far beyond the common.

Doc's ears and nostrils told him no one occupied the apartment. He tried the door. Locked! He exerted what for his great muscles was moderate pressure. The door swished inward, lock torn out.

- The Land of Terror (1933) Chapter 10