The title character is a US army Captain of Native American descent who is asked to investigate the murder of an Indian agent. His only clue is "April morning", the last words spoken by the victim. Can he unravel the mystery before the clock runs out?
| Actor | Role |
|---|---|
 Lee Van CleefCapt. Apache | Capt. Apache |
 Carroll BakerMaude | Maude |
 Stuart WhitmanGriffin | Griffin |
 Percy HerbertMoon | Moon |
 Elisa MontésRosita | Rosita |
 Tony VogelSnake | Snake |
| CCharles StalmakerO'Rourke | O'Rourke |
 Charly BravoSanchez | Sanchez |
| FFaith CliftAbigail | Abigail |
 Dee PollockBen | Ben |
 Dan van HusenAl | Al |
 Hugh McDermottGen. Ryland | Gen. Ryland |
| GGeorge MargoSheriff | Sheriff |
 José BódaloGeneral | General |
 Ricardo PalaciosSergeant | Sergeant |
| JJohn ClarkNot listed | Not listed |