PROBLEM IN SOLID BY GEORGE O. SMITH Illustrated by Orban [Transcriber's Note: This etext was produced from Astounding Science-Fiction, October 1947. Extensive research did not uncover any evidence that the U.S. copyright on this publication was renewed.] Martin Hammer should have been prepared for anything. As the world's foremost producer of motion pictures, he should have taken any situation from earthquake to fatherhood without a qualm or a turned eyebrow. But Hammer had not seen everything--yet. A noise presented itself at Hammer's office door. Not the noise of knocking or tapping, nor even the racket made by attempts to breach the portal with a heavy blunt instrument. It was more like the sound of a dentist's drill working on wood, or perhaps one of those light burring tools, or maybe even a light scroll saw. Then, with all the assurance in the world, a man's hand came through the door, the fingers clenched about an imaginary doorknob. The hand swung an imaginary door aside and as it moved, the wood of the real door fell to the floor in a pile of finely-ground sawdust. Once the imaginary door was thrust aside, the rest of the intruder entered, leaving the exact outline of his silhouette in the door. He smiled affably and said, "I trust I'm not intruding!" He was still holding the imaginary door open with his right hand. As he finished speaking, he stepped forward a step, turned, pulled the imaginary door shut a few inches, transferred it to take the inside knob in his left hand, and then stepping carefully forward, he thrust the imaginary door closed, his hand clenched around the imaginary knob. The act ended as his hand entered the real doorknob and there was the high-pitch whine of metal against metal like cutting a tin can with a bandsaw. The intruder turned, walked across the office, and stood there in front of Martin Hammer. From a pocket he look a cigarette and a match and lit up, blowing a cloud of fragrant smoke into the air. "I am delighted to meet you," he said. At which point, Martin Hammer blew up. He had been patient. He had been astounded. He had been sitting there with his chin getting lower and lower and lower as this ... this character walked through his door with all the assurance in the world. Then the bird had the affrontery to behave as though he had not invaded Hammer's office; had not ruined a fine oak door; and as though Hammer should have been glad to see him. What added fuel to Hammer's explosion was the fact that the intruder seemed absolutely unaware of the ruination of the door. "What the--" yelled Hammer. He leaped to his feet, ran around his desk, and faced the intruder angrily for only an instant. Hammer launched himself at the intruder with intent to do bodily harm, mayhem, and perhaps a little bit of second-degree murder that might be juried into justifiable homicide.