The Frontier Trail.

Dolly Mainard, en route to her father, a major at Fort Blaine, is escorted through dangerous Sioux territory by a cavalry detachment and Army scout Jim Cardigan. When Captain Blackwell offends some braves of Chief Gray Wolf's tribe, Jim is sent ahead to the Indian camp to ask for peace. Imprisoned by the Indians, he sends a message to Blackwell not to advance; Donlin, a renegade scout, tears the note in such a way that the message is distorted, and the entire force is killed. When Jim escapes, he is accused of treason by Blackwell, court-martialed, and sentenced to death; however, he escapes and rescues Dolly, her father, and Blackwell from Donlin's band of renegades. Jim discovers the missing portion of the note in Donlin's hat, proving his innocence. Dolly remains to become his wife.