Another in the "Doom of London" series, in which the author sounds a clarion call of potential disasters that may fall upon the great city. Here he relates a tale of air pollution. Excerpt: They crawled along through the black suffocating darkness, feeble, languid, and sweating at every pore. There was a murky closeness in the vitiated atmosphere that seemed to take all the strength and energy away. At any other time the walk to Clarence Terrace would have been a pleasure, now it was a penance. They found their objective after a deal of patience and trouble. Hackness yelled in the doorway. There was a sound of footsteps and Cynthia Grimfern spoke.