Jack Armstrong #3

In "Jack Armstrong in the Lost Valley of Ice," the all-American boy and his companions encounter a giant bear in a frozen landscape while investigating a mysterious case. The story involves Rex Blaine examining ballistic evidence from two guns to determine which fired identical bullets, and features action sequences including Jack banking away from machine-gun fire and catching an attacking plane between his gunsights. A child becomes trapped on a ship's deck, leading Helen to brave a fierce furnace to reach the endangered youngster.