How about something like:
When a nerdy teen realizes cryptic graffiti contain clues to a series of child abductions he must struggle alone to crack the code and rescue the children because no one believes him.
(32 words)

Or maybe:

A nerdy teen struggles alone to crack the code in cryptic graffiti because no one believes him that they are clues to a series of child abductions.
(27 words)

Although that may be too succinct.

Whatever, in drama ?”become a town hero” is never the direct, overt objective goal. ?It’s the reward that accrues from ?achieving the objective goal which in this case is cracking the code, ?apprehending the villain, saving the children.

?And ?the setting, a small town, while germane to the script is not necessary to include in ?the logline. ?Rather, I suggest that a more important factor is the ?initial obstacle to achieving his objective goal: ?no one believes him. ?He must endure the slings and arrows of derision and rejection by his peers and his elders. ?He must trust his intuition, his own intelligence in defiance of what everyone else thinks and says.

Anyway, I think this has the makings for an interesting movie that would appeal to the all-important youth market. ?Best wishes with your writing.

fwiw