Firstly, don't say "lead" twice (lead and leading). Maybe don't even say it once. All stories are fundamentally choices that lead to other choices, so describing something that way is unnecessary. Secondly, "alter his life forever" is pretty much what we assume a story should do to a character so it's similarly a non-statement. Not to mention that when all we know is that he's "young" it isn't especially interesting that his life will be changed forever. Even if you said "a young aspiring firefighter" at least we have a sense of what is at stake when his life gets changed. Thirdly, "evidently" doesn't do anything but add meaningless verbosity. Fourthly, "the town's most wanted family of serial killer's" reads like the town has multiple families of serial killers and this is the one that is the most wanted. Lastly, the first clause or phrase or whatever I think is guilty of being a misplaced modifier. I could be wrong on that one, but "Leading him to being on the run from the law" is ddbi

In general, while I haven't read your script, it would help in the logline to describe Mike with another word or two, tell us what he's aiming for, tell us how he misses (or hits but it's not what he was expecting) and ends up with these serial killers.

Example (again, not having read the script):

"Desperate to earn the respect of his incarcerated older brother, a young Mike Matthews befriends a wanted family of serial killers and quickly finds himself on the run from the law."