Uncle Rob searched his mind for a clue, and did not find it. Lambert's voice was resolute and stern, and he was about to arrest a man to save whose life Uncle Rob would have laid down his own; and yet here he was unbosoming himself in a friendly and confiding way to the very person against whose happiness he was conspiring. It would have taken a wiser head than Uncle Rob's to solve the enigma. What Lambert said next did not help to make matters clearer. "And don't take it too much to heart," he said, with a soothing pat on Uncle Rob's shoulder. "I know what I'm about, so don't take it too much to heart. It's the advice of a friend, Robson." "There's cold comfort in it when the charge is murder, and a man's life is hanging to it," said Uncle Rob. "Perhaps so, perhaps so, if you look at it only from the outside; but there's another view." "What is it?" "That's _my_ secret. When I let it out you'll see what I'm driving at. I've done one or two things in my time, and this will be the climax." He smacked his lips with a relish, and repeated, "The climax. I put it to you, Robson, old man, whether it isn't better that the arrest should be made by a friendly hand than by the hand of a stranger? I'm not the only one who's itching to get the credit of clearing up a mystery that's set all London ringing; and we're not half done with it yet, not half done. It's a feather in one's cap to be mixed up with it." He rubbed his hands. "No wonder others are keen upon it, but there's only one man in England that's got his finger on the pulse of the mystery, and that's the man that's talking to you now, and taking you, in a manner of speaking, into his confidence." "And that is why you are going to arrest my son-in-law," said Uncle Rob, rather bitterly. "And that is why," said Lambert, cheerfully, "I am going to arrest your son-in-law on the charge of murdering his father, Mr. Samuel Boyd, of Catchpole Square. Before long you'll be shaking me by the hand, and thanking me for what I'm doing." "Then you don't believe him guilty?" said Uncle Rob, eagerly. "Don't ask me for opinions. I've been open with you for old times' sake, but my opinions, for the present, I keep to myself." He looked at his watch. "What time are you due at the station, Robson." "I must be there within the hour. I wish I'd resigned, or asked to be suspended." "The worst move you could have made. Duty's duty. There was a Roman father once--I don't remember his name--that sent his own son to execution, and looked on while it was done." "What do you mean?" asked Uncle Rob. His voice trembled, his fingers twined convulsively. "It's plain enough," said Lambert, half roughly. "You're on night duty at Bishop Street Station." "And the charge will be laid there!" cried Uncle Rob, a cold perspiration breaking out on his forehead. "It's in the district; it's the nearest station. There's no help for it; I wish there was."