He swung his body well out, let go--and dropped.

With the impetus he smashed against a wall, was flung back from it in a sort of rebound, and his hands closed, gripping fiercely, on banisters.

It had been the stair well beyond any question of doubt, but his swing had sent him clear of it.
Above, they had not yet reached the skylight.

Jimmie Dale snatched a precious moment to listen, as he rose, and found himself, apart from bruises, perhaps unhurt.

There was commotion, too, in this house below, the alarm had extended and spread along the block--but the commotion was all in the FRONT of the house--the street was the lure.
Jimmie Dale started down the stairs, and in an instant he had gained the landing.