Mentally he counted the seconds as each pulsation within the tube was transmitted to his hand. At the tenth he stiffened. There was a dull thud, a little puff of smoke, and a grating and jangling as of breaking glass. Then he was inside, pacing down the center aisle of the main office. He had no need for a torch. The place was brilliantly lighted with overhead carboliers, and he knew that he was clearly visible from the street. In rapid strides he reached the far end of the office, where an enormous vault door of _arelium_ steel was imbedded in a frame of _kartite_. That frame was anchored in natural rock piers ninety feet below. The entire structure was as impregnable as human intellect could make it. Jimmy Starr leaped over the low railing that separated the vault from the office proper. Again he opened the little carry-case and from a lower compartment took out a tightly rolled Martian papyrus. He was working fast now, putting into action a plan that he had formed on his visit to this office earlier in the day. Then, while he had stood discussing the financial status of Triplanetary Shipping with one of the Trust Company officials, he had managed to slip out a tiny camera and, unobserved, take a quick photograph of the rear wall of the office. Back in his own apartment it had been the work of a few moments to transfer the scene on the negative onto this elastic papyrus. He stood up on the railing, fastened the two ends of the papyrus to the side wall; then, utilizing all his strength, stretched it across the full width of the office to the opposite wall. Finished, he slipped behind the screen with a gay laugh. Let a passerby gaze in the street window now. He would see a deserted office with the unmolested vault in clear view. From the street no one could know that vault was an enlarged photograph on a screen, and that behind that screen crouched the most wanted cracksman on Mars--the Nebula! He spent a moment surveying the massive vault. "Craig-Orlan, Series A. Model Four," he muttered appreciatively. "Mercury time lock, rondulated tumblers, protected with individual micacaps. This is going to be tough." He took from the carry-case a pair of earphones, snapped them on and pressed their connection to the panel just below the main dial. Slowly he began to turn that dial, straining his ears for tell-tale clicks. The silence of the office pressed down upon him. Far off sounded the hollow roar as the night Earth Express blasted down to its cradle. For several minutes he continued. Then his brow furrowed in a frown. "Must have a shield of some kind behind it," he muttered. He opened the carry-case again, drew forth a tiny electrolic drill with a wedge-shaped bit. A low hum sounded as he switched the drill on and pressed it against the panel.