Upon turning the corner, the footsteps advanced a pace or two, faltered, slackened, stopped.

For an instant there was silence.
The doctor knew that the man had been struck by his attentive figure, and was pausing to regard it, to consider it.

What would be the result of the inspection?
In a moment the doctor knew.

The footsteps sounded again, this time in retreat.
On this the impulse of the doctor to flee changed, giving way to a strict desire and determination.

He was resolved to interview this night-wanderer, to see his face.