Sergeants 3 (1962)

Under very suspicious circumstances, the telegraph line is out in Medicine Bend, a dusty town in 1870s Indian Territory. To investigate the situation and shed light on the mystery, U.S. Cavalry First Sergeant Mike Merry assembles a detail and proceeds at once to the town, along with Sergeant Chip Deal and Sergeant Larry Barrett. On their way, they cross paths with the trumpet-playing former slave, Jonah Williams, who joins in, dreaming of becoming a trooper. Now, against the backdrop of the picturesque but unforgiving landscapes of the Wild West, a sinister conspiracy is afoot as no Sioux is on the warpath. But, who is behind the Medicine Bend incident? Can the three sergeants get to the bottom of it and live to tell the tale?