Malcourt could not get in without it.

And the doors were barred and chained.
Slipping the key into his pocket he opened his door, and, treading quietly through the silent house, descended to the great hall.

With infinite precaution he fumbled for the chains; they were dangling loose.
Somebody, too, had drawn the heavy bars, but the door itself was locked.
So he cautiously unlocked it, and holding the key in his hand, let himself out on the terrace.
And at the same moment a shadowy figure turned in the starlight to confront him.
"Shiela!" "Is that you, Mr.Hamil ?" "Yes.

What on earth are you--" "Hush! What are _you_ doing down here ?" "Louis Malcourt is out.

I forgot to leave a key for him under the yellow rose--" "Under the rose--and yellow at that! The mysteries of the Rosicrucians pale into insignificance beside the lurid rites of Mr.Malcourt and Mr.
Hamil--under the yellow rose! Proceed, my fearsome adept, and perform the occult deed!" Hamil descended the terrace to the new garden, hung the key to a brier under the fragrant mass of flowers, and glanced up at Shiela, who, arms on the balustrade above him, was looking down at the proceedings.
"Is the dread deed done ?" she whispered.
"If you don't believe it come down and see." "I?
Come down?
At _two_ in the morning ?" "It's half-past two." "Oh," she said, "if it's half-past two I might think of coming down for a moment--to look at my roses....