Tom and Bronte, the engine's builder, discover that the electrical generator acquired for the Silver Streak has a manufacturing flaw. After correcting the flaw, the engine produces even greater power than he had earlier predicted. He tries to telephone Ruth with the good news to reconcile with her, but she has left Chicago to travel by train to California. Ruth discovers en route that infantile paralysis (polio) has broken out among the dam's construction crew and detours to the site only to find that Allen has contracted the disease. When a doctor informs her that Allen will die within 24 hours unless he receives treatment from an iron lung respirator, Ruth telephones her father to have the machine shipped to the dam by airplane. Dexter is told that the iron lung is too heavy for any transport airplane to carry and cannot be disassembled. Tom and Tyler persuade Dexter to take a gamble on the Silver Streak as Allen's only hope.