It was not, then, man to man. There were two to one. Justice might be defeated were he to risk the unequal encounter. He determined to call in the assistance of the officers in the Square. But before he left the house, which was being watched from the front and the back, it would be as well to make sure of the murderer and his companion, so that they should have no possible means of escape. He took from his pocket the key of the room, which he had picked up a few hours ago; with a steady hand he inserted it in the lock, and gently turned it, being unable to prevent the sound of a slight click. Then he crept noiselessly down stairs, opened the street door, closed it softly behind him, and stepping into the road, put a whistle to his lips. The summons was not instantly obeyed, and he blew the whistle again, and looked anxiously around. The faint sound of another whistle presently answered him, and in two or three minutes the detective was by his side. "I was at the back of the house, sir," said the detective, in apology, "giving directions to one of my men, Parrock, a sharp fellow. You have discovered something," he added, noting Frederick's agitation. "I have found my father's diary," said Frederick, speaking rapidly, "and a Will he made two or three days before he was murdered." "Making you all right, I hope," said the detective. "Yes--but that is of no consequence. The diary, which I have read, leaves no room to doubt that my father was murdered by his wife's accomplice, Pelham. The evidence is conclusive, and he cannot escape the law, once we have him safe. He must be arrested this moment. He is in my father's room. I would have secured him myself, but he has another man with him, and I did not care to run the chance of two against one." "He has a woman with him, you mean," said the detective, "not a man." "A man, I mean," replied Frederick; "I saw him with my own eyes." "And I, with _my_ own eyes," rejoined the detective, "saw Mrs. Holdfast enter No. 118 this evening, in company of Richard Manx, otherwise Pelham. Attend to me a moment, sir. I see through it all. Mrs. Holdfast accompanied him to-night into the house. Never mind the motive--a woman's motive, say--curiosity, wilfulness, anything will serve. Pelham does not want her company--she forces it on him. What does he do then? He dresses her in a suit of his clothes, so that they may not attract attention when they leave Great Porter Square to-night for good. She is a noticeable woman, sir, and has a style about her which one can't help remarking. The person you saw was Mrs. Holdfast, dressed in man's clothes. They are both, you say, in the room your father occupied?" "Yes, and I have locked them in, so that they cannot easily get out of it." "Did they hear the key turn?" asked the detective, anxiously.