A retired cavalry soldier is forced to partner with a Cheyenne Indian to track down a serial killer who has kidnaped his daughter.

Btw that is why I dropped 'forced' from my logline example lol. Great Comment!

If you must use a must in your logline, then you must have an or else, or else the must won't have meaning or stakes.

The lead character Must do this Or else this bad thing will happen.

A logline guru on this site once stated:
If you have two opposites who must team up together, you must (In the logline) give us the compelling complication which leads to their unlikely alliance. Likely this will be the hook of your logline so don’t leave it out. Your logline will greatly improve by adding it.

When his daughter is kidnapped, a retired cavalry soldier partners with a Cheyenne Indian to track down the man who took her.
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I changed the serial killer part because you describe him as a killer but then you say he kidnapped the daughter, killing and kidnapping are two different things, I would leave the serial killer part to the actual story and not in the logline.

How about a retired cavalry soldier whose wife/brother/family/sister was killed by an Indian war party?....

Maybe play up the idea that he's traumatized by something that the Native Americans did to him during the war so it contrasts with the idea that he has to team up with a Cheyenne Indian to save his daughter. Works for me, otherwise.