Hetherwick followed his companion across the Strand, into the Adelphi, and to the house they wanted—an old Adams mansion, now divided into flats. Matherfield did not take the trouble to ascend to the upper regions; he sought and found a caretaker and put a question to him. The man shook his head.
"Dr. Ambrose, sir?" he replied. "Oh, yes, Dr. Ambrose lives here—38. But he ain't in, sir—ain't at home, in fact. He's been away three weeks or so—don't know where he is."
With a meaning look at Hetherwick, Matherfield drew the caretaker aside and talked to him for a few moments; the man presently turned and went downstairs to the basement from which they had summoned him.
"That's all right," remarked Matherfield, with a wink. "He's going to let us into Ambrose's flat. Didn't I tell you we shouldn't find Ambrose here? Not he! I should say he's off!"
"Supposing he returns—while we're here?" asked Hetherwick.
"Wish he would!" chuckled Matherfield. "Nobody I want to see more! If he did, why, I should just ask him to take a little walk with me—to explain a few matters. But he won't! Here's the man. We'll go up."
The caretaker reappeared with a bunch of keys and led the way to a flat at the top of the old house. He unlocked a door and stood aside.
"You needn't wait," said Matherfield. "I'll shut the place up again when we leave and let you know. All right."
He walked in, with Hetherwick at his heels, as soon as the caretaker had gone, and, once inside, closed the door carefully upon himself and his companion. But Hetherwick, after a first glance at the sitting-room into which they had entered, a somewhat untidy, shabbily furnished place, went straight to the hearth and pointed to a framed photograph, time-stained and faded, which hung over the mantelpiece.
"There's a striking and significant piece of evidence—at once!" he exclaimed. "Do you know what that is, Matherfield?"