When a horde of zombies kill the sheriff of a sleepy frontier town, a penitent gunslinger, sentenced to hang, leads the townsfolk in their desperate fight for survival.

>>>incapacitates the sheriff

Only incapacitated?? Seems? weak to me.

How about something like:

Saved at his hanging by a zombie invasion, a gunslinger stays and fights for the people who want him dead rather than flee town for his life and freedom.

>>Saved at his hanging
Open with him being marched from the jail to the scaffold where he's about to be hung, jeered on by a mob of townspeople.? As the noose being put around his neck -- the zombies attack.

>>>a gunslinger stays and fights
Give him a clear cut opportunity to flee town in the ensuing chaos, save his live.? Then, for whatever reason, a reversal: he opts to stay and fight for the lives of the very people who want to see him hanged.? This implies a morally redeeming beat-- but there's no need to be explicit because that's the subjective storyline and loglines are about the objective storyline.

fwiw

>>>incapacitates the sheriff

Only incapacitated?? Seems? weak to me.

How about something like:

Saved at his hanging by a zombie invasion, a gunslinger stays and fights for the people who want him dead rather than flee town for his life and freedom.

>>Saved at his hanging
Open with him being marched from the jail to the scaffold where he's about to be hung, jeered on by a mob of townspeople.? As the noose being put around his neck -- the zombies attack.

>>>a gunslinger stays and fights
Give him a clear cut opportunity to flee town in the ensuing chaos, save his live.? Then, for whatever reason, a reversal: he opts to stay and fight for the lives of the very people who want to see him hanged.? This implies a morally redeeming beat-- but there's no need to be explicit because that's the subjective storyline and loglines are about the objective storyline.

fwiw

You did a lot of work to avoid the word Zombie. We all think Zombie, just say Zombie. How the Zombies are created isn't important, so you can drop that.

Penitent and seeking redemption is much the same so chose one and work with that.

A gunslinger sentenced to hang leads a town in a war against Native American zombies.

Now add some colour to that and you're done.

I'd see it.