When the suicide of Trent Warner is discovered, a group of his friends must fulfill his dying wish by delivering 100 letters he composed before his suicide, in doing so they will discover that Trent Warner?s death is not as simple as the police report makes it out to be.

You specified that the main characters are the group of friends which means you have a multi protagonist plot. These type of scripts are hard to write and execute well on the page seeing as a single protagonist plot is a feat on its own. I think best to pick one character as the ring leader the head poncho and use that character as the main point of view character to tell the story with.

The motivation for the characters to deliver letters after their friend dies feels weak and more of a convenience. What is it that happens that, beyond a doubt and without much explanation, motivates someone to need to deliver a bunch of letters?

The circumstance of the friends death is not an obstacle it is a revelation that could motivate a mid act 2 change of approach but not oppose the characters from achieving their goals.

I think the concept needs re thinking here are some questions to consider.
What single character will drive the story and have it be about? What is that character’s clear and well motivated goal?

Unlike before use these questions as pointers to help with a re draft the logline answering them in a post will likely not be as productive.

Hope this helps.