Alaskan railroad magnate Curtis Gordon hires engineer Dan Appleton to design a railroad route up the Salmon River to the rich gold country. Gordon turns down the engineer's proposed route in favor of his own, and Appleton quits. Murray O'Neil, a rival builder, hires him and falls in love with his sister Eliza, while Appleton courts Natalie, Gordon's stepdaughter. Following Appleton's plan, O'Neil lays the trail with a bridge crossing the river in face of Gordon's opposition. When the bridge is near completion, the workmen leave in fear of ice floes. Working desperately, O'Neil and Appleton manage to complete the work just before the ice breaks on the bridge, which holds fast. The road is completed and the lovers are united.