A teenage girl returns home to her whole family executed and must go undercover to find her family's killers where she finds that she isn't fully human.

This is basically what da Vinci code is

"When her family is executed by the ruthless leader of the dark cranes, an introvert must infiltrate their secret organization for revenge but along the way discovers she may not be entirely human."

I think it is becoming evident that the mixture of genres in the logline is hindering most readers understanding of your story.

I strongly suggest taking on board the above comments and focusing on the murder mystery in the logline and not mention the supernatural elements at all.

Example:
After the family of an introvert girl is murdered she must flee her home to escape death and goes on the road to catch the mysterious looking killer.

If you use the antagonist description as a hint at super natural you can suggest that there is a genre mix in the story. Other wise it doesn't matter what race the girl is or isn't her story still starts after her family is killed and she her action is to catch the killer.

What is a Dark Crane? What is a Hidden?

Version #3:
Brianna, an introverted girl, has intense hearing skills and reflexes. She experiences horrific flashbacks of a murder she doesn?t know she commited. One night she returns home to her family murdered by Luther Kin, leader of the Dark Cranes, who also leaves her for dead. Surviving her attack she pursues Luther Kin where she finds that her parents were the leaders of the Hiddens and that she is the key to Hidden survival from Dark Crane slavery.

With this version of your logline, you?ve created more questions than you have answered.

Hidden, Dark Crane, I know these are races but they take me out of your story. Mix your two versions. I am not sure someone encounters memory loss, they may experience it.
Forget about all the colour and movement. Just list the story elements. A girl, murdered family, wants to solve murder. So what is stopping her?
In your logline she discovers she isn?t human, so does that help or hinder? What does that mean in the story?
I can feel that there is a strong story line in there. It just needs to be teased out.

This describes a situation, what is your lead characters goal?

Version #2:

An introverted girl encounters memory loss, horrific visions and the murder of her family where she discovers that she is part human, part Dark Crane and part Hidden.

When her family is executed, (This should be the beginning of the logline)

by a ruthless (have know idea who, you should add this)

an (Adjective) girl must go undercover (You should tell us where she is going undercover)

To seek revenge but discovers she may not be entirely human.

Hope that helped, good luck with this!

Agreed with Gilgamesh.

What genre is this story?

What time period and location?

The need for the girl to pursue the killers could be explained if the story was set in the old west or 17th century Prussia for example.

But the combination of genres as a result of the directive and scifi elements in the logline could confuse readers.

Hope this helps.

Answering the "must" is important. If it seems unrealistic in a logline it will remain so in your script. Looking forward to reading version2

Dear kbfilmworks, thank you for replying to my logline, it was very helpful. But the title reflects a species. A Hidden is an unknown species that Brianna didn't know she was.

The first part of this logline makes for a good story in and of itself: "When a teenager returns home from a field trip and discovers her entire family has been executed, she must go undercover to find their killers."

That last bit in your logline about her discovering that she isn't fully human seems to come out of left field though. It turns what reads like a standard detective story into some kind of sci fi horror.

If the bit about her being not fully human is related to her family's murders, you'll want to tie them together somehow and reshape the logline into something that befits a sci fi/horror genre.

The other thing that needs explaining is why must the girl go undercover to find the killers? Why not just go to the authorities?

hope this helps

On a mission to find the killers who murdered her family, an introverted teenage girl discovers a hidden side of herself: she is part human, (part vampire, werewolf, alien, etc).