Be sure you come again to-morrow.' 'Yes, I promise you to come; good-night.' 'Good-night.' Mary went back to the stable.

The door was still open, but how could she be sure that it would be open to-morrow?
There was no other access that she knew of to the quadrangle, except through the old part of the house, and that was at times inaccessible to her.
She found a key--a big old rusty key--in the inside of the door, so she shut and locked it, and put the key in her pocket.

The door she supposed had been left open by accident; at any rate this key made her mistress of the situation.

If any question should arise as to her conduct she could have an explanation with Steadman; but she had pledged her word to the poor mad old man, and she meant to keep her promise, if possible.
As she left the stable she saw Steadman riding towards the gate on his grey cob.

She passed him as she went back to the house.
Next day, and the day after that, and for many days, Mary used her key, and went into the quadrangle at sundown to sit for half an hour or so with the strange old man, who seemed to take an intense pleasure in her company.