When her amnesiac daughter awakens next to a headless, burnt corpse in the woods, a bipolar detective must uncover the secrets of a small town and its paranormal history, to find out the truth and prove her daughter?s innocence.

I like it, this really sounds interesting.
Well done!

I would shorten the logline and add a bit of tension between the daughter and mother (why not…):
After her estranged daughter wakes up beside a headless corpse, a bipolar detective must uncover the paranormal secrets of a small town to prove her daughter?s innocence.

The sizzle (I’m looking at you DPG…) here is her daughter being in trouble with paranormal stuff, therefore, best you cut anything that isn’t necessary to describe that. As far as the plot goes, finding out the truth is implicit in her primary goal – to prove the daughter innocent, so you don’t need it in the logline.

All the best developing this concept.