It was exactly three.
"I have Craig here in the Professor's garage, locked up.

If our plan has succeeded, come at once.

I am waiting here for you." Quest's eyes shone for a moment with satisfaction.

Then he sent off his answering message, put on a duster and slouch hat, and left the house by the side entrance.

In a few moments he was in Broadway, and a quarter of an hour later a taxicab deposited him at the entrance to the Professor's house.