As he drew near to the house he saw someone about to enter.

He ran forward.

It was Gilbert.
'How does the library get on ?' he asked, with an abruptness which surprised Grail.
'Oh, all the carpenter's work is finished.' 'Any books come yet ?' 'No, not yet.' 'Ah! Good-night!' He passed on, leaving Gilbert still in surprise, for it was perhaps the first word Ackroyd had spoken to him concerning the library.
Luke began to run, and did not cease until he was in Brook Street in front of the library.

He tried to look in at the windows, but found that the blinds were drawn.

A policeman passed and scrutinised him.
'Do you know whether any one lives on these premises ?' Luke asked at once.
He excited suspicion, but after a short dialogue the constable showed him the approach to the caretaker's house.