Surely, he would soon come back, lest he should miss the keeper of the diamonds.
I had very little hope that, even on the chance of my arriving while he was away, he would have left the door open.

Nevertheless I tried the handle, and to my surprise it yielded.
"That must be because the lock's broken and only a bolt remains," I thought.

"So he had to take the risk.

All the better.

This looks as if he'd be back any minute.