Dr. van Heerden could admire the ingenuity of his enemy and could kill him. He was a man whose mental poise permitted the paradox of detached attachments. At first he had regarded Stanford Beale as a smart police officer, the sort of man whom Pinkerton and Burns turn out by the score. Shrewd, assertive, indefatigable, such men piece together the scattered mosaics of humdrum crimes, and by their mechanical patience produce for the satisfaction of courts sufficient of the piece to reveal the design. They figure in divorce suits, in financial swindles and occasionally in more serious cases. Van Heerden knew instinctively their limitations and had too hastily placed Beale in a lower category than he deserved. Van Heerden came to his workroom by way of the buffet which he had established for the use of his employees. As he shut the steel door behind him he saw Milsom standing at the rough wooden sideboard which served as bar and table for the workers. "This is an unexpected pleasure," said Milsom, and then quickly, as he read the other's face: "Anything wrong?" "If the fact that the cleverest policeman in America or England is at present on the premises can be so described, then everything is wrong," said van Heerden, and helped himself to a drink. "Here--in the laboratory?" demanded Milsom, fear in his eyes. "What do you mean?" "I'll tell you," said the other, and gave the story as he had heard it from Hilda Glaum. "He's in the old passage, eh?" said Milsom, thoughtfully, "well there's no reason why he should get out--alive." "He won't," said the other. "Was he followed--you saw nobody outside?" "We have nothing to fear on that score. He's working on his own." Milsom grunted. "What are we going to do with him?" "Gas him," said van Heerden, "he is certain to have a gun." Milsom nodded. "Wait until the men have gone. I let them go at three--a few at a time, and it wants half an hour to that. He can wait. He's safe where he is. Why didn't Hilda tell me? I never even saw her." "She went straight up from the old passage--through the men's door--she didn't trust you probably." Milsom smiled wryly. Though he controlled these works and knew half the doctor's secrets, he suspected that the quantity of van Heerden's trust was not greatly in excess of his girl's. "We'll wait," he said again, "there's no hurry and, anyway, I want to see you about old man Heyler." "Von Heyler? I thought you were rid of him?" said van Heerden in surprise, "that is the old fool that Beale has been after. He has been trying to suck him dry, and has had two interviews with him. I told you to send him to Deans Folly. Bridgers would have taken care of him." "Bridgers can look after nothing," said Milsom. His eyes roved along the benches and stopped at a worker at the farther end of the room.