When the ultimate betrayal comes to surface, 8 friends will become enemies and only 1 will be left standing.

8 friends will become enemies with the betrayer or each other? It's just mush.

"Ultimate betrayal " is vague.? What does that mean?

And the logline also contains a spoiler; it gives away the ending (only 1 will survive). That is something a logline should never do.

Hi Kathryn,

As variable said earlier, this is a tagline for a movie, not a logline.

As a logline it's incredibly vague. You could describe a crime thriller in vein of Reservoir dogs or a high school comedy where 8 friends are vying for the same guy for example.

Until we get more details, it will be difficult to help you develop the concept or improve on the logline.