In 1876, a scout leads cavalry men to an Indian wigwam but there's no one there. The scout figures that Custer will find plenty of Indians when he crosses between the Bighorn and the Little Bighorn Rivers in four hours. An Indian shoots the scout in the back and the cavalry men return fire…
And three National Guardsmen, Langsford, Connors, McCluskey are at their tank in 1964 when they hear the sound of gunshots. Connors suggests they go take a look and the other two go along with him. They find an empty wigwam and McCluskey points out their near where Custer and the 7th Cavalry fought the Sioux. Connors finds a canteen in good shape and figures it belonged to the 7th Cavalry. Langsford is unimpressed but they're interrupted when a wind picks up out of nowhere and then dies out as suddenly as it came. Connors talks about how he read up on everything about the Battle of Little Bighorn and how Custer was caught by surprise by unanticipated enemy numbers. Custer split his force into three units and they were slaughtered. Langsford points out the canteen isn't an antique and someone must have planted it as a gag. The wind comes up again and McCluskey insists they go back to the tank.
The men return to their tank but hear an Indian war cry from behind them. Connors dismisses it as the wind and McCluskey reluctantly agrees. They return to their command post and Connors reports to his superior, Captain Dennet. He tells Dennet they heard gunshots but the captain doesn't believe him and wonders if they were drinking. Dennet traces out their route, which matches the route Custer's men took. Dennet insists they heard Indians and found a canteen and a wigwam. According to the historical record, Custer's scout found a wigwam before the battle. Dennet doesn't believe him and sends them out.
In the field, the three men spot a column of smoke in the distance and hear drumbeats. Langsford thinks it's a joke but McCluskey says that Custer saw a smoke column before the battle. Connors knows the same thing but Langsford insists they're both nuts. The wind picks up and they hear hoof beats just over the horizon, accompanied by a dust cloud and war cries. McCluskey opens fire and Langsford stops him, but a horse rides over the ridge without a rider. Langsford wonders what happens if they follow the same trail that Custer did. Connors figures they'll be at a massacre and Langsford wonders if he plans to stop it. Connors says that they'll either stop the massacre… or join it.
The camp calls the tank and Dennet asks for a position report. He tells them to report back within the next half hour but Connors cuts off. Dennet tells Lt. Woodard to take a jeep and bring them back if he has to shoot them in the leg to do it.
The three Guardsmen continue along the trail but don't find anything. Langsford figures the entire thing is an illusion but Connors and McCluskey remember that Custer's men found an Indian village an hour before the battle. Langsford leaves on foot for the command post, goes over a ridge… and sees an abandoned Indian village. He calls his comrades over and McCluskey goes in on foot. Connors explains that at this point Custer's men were doomed. McCluskey returns… with an arrow on his back.
Woodard returns to the command post and reports that they found the tank and note on it. The note is from Connors and says they're heading for the battle to join the 7th Cavalry.
Langsford and Connors help the wounded McCluskey toward the ridge overlooking the battle. They come over the top and see the fight below. They prepare their guns and charge into battle.
Dennet's men find no trace of the three missing Guardsmen. As they prepare to leave, Woodard spots a memorial to the massacre… and the names Connors, McCluskey, and Langsford are on it. Woodard wonders if it's a coincidence and Dennet wonders what might have happened if they'd taken the tank with them.