Chief Yellowstone and Colonel James Reid negotiate a treaty setting a final boundary between lands owned by Indians and areas open to white settlers. The Wachupi River, known as Massacre River for the many bloody battles between Indians and settlers, is agreed upon as boundary. No settlers are allowed to cross this river into Indian territory. The Indians promise to stick to their side of the river. However, Chief Yellowstone warns Colonel Reid that some of his braves who wish to wage war might be hard to control and they could attack wagon trains. Colonel Reid's son, Junior Lieutenant Randy Reid is serving under his father. Two of his best friends, Lieutenants Phil Acton and Larry Knight are also attached to the cavalry unit serving at the isolated outpost. The two junior officers compete for the affections of Kitty Reid. Kitty Reid is Lieutenant Randy Reid's sister and Colonel James Reid's daughter. Although Kitty is engaged to Phil Acton she realizes that she's actually in love with Larry Knight. At a party given before her departure for St. Louis she sets things straight. Disappointed by the news, Phil wishes good fortune to Larry and Kitty. With the arrival of the stagecoach in town, newcomer Laura Jordan reveals that she's the new part-owner of the Blue Star Hotel and Gambling House. The other owner, Burke Kimber, tries to buy Laura out so that he could be sole owner but Laura refuses the offer. Through a twist of fate, both Lieutenants, Larry Knight and Phil Acton, get acquainted with pretty saloon owner Laura to Kitty's dismay. When Kitty's new beau Larry starts showing a romantic interest in worldly Laura, Kitty's protective brother, Randy Reid, looses his cool and decides to face Larry to defend his sister's honor. Things get more complicated when Laura's business partner, Burke Kimber, forcibly tries to push Laura into signing her share of the business over to him. This forces Larry to intervene in Laura's behalf with dramatic consequences.