When a Craigslist-swinging-meetup goes bad and the voyeruist find herself trapped with a serial killer, she must out-clever the killer before times-up as gagged-bate for the killer’s next victim.

Thanks all for the feedback!

I am finding the gagged bait a stumbling block. Being held by a serial killer "bond and gagged" is a given. Also her reason turning up. Swinging is enough to set the scene, that she likes to watch is unneeded detail at this point in time. taking this out gives the line a pace which I think would be reflected in the story.

Ah, I totally see how the swingers date looks unimportant and how the protagonist looks helpless.

another try:

When a Craigslist-swinging-meetup goes bad and the voyeruist find herself trapped with a serial killer, she must out-clever the killer before her time is up as gagged bate for the killer's next victim.

I updated the logline (or, should I keep the original and just write changes below?).

Also this is a short, so the story is only describing one event (the whole meetup until resolution).