A grieving father takes a job as a janitor to break into a building and gatecrash a Christmas party to exact revenge on those who committed an unspeakable act against his son.

This logline had me HOOKED until you said "unspeakable act". The unspeakable act is directly spoken of when you say, "unspeakable act". However, changing unspeakable out for a different adjective fixes this problem immediately and leaves you with a very very well polished logline that sells. "Heinous" "unforgivable" "destructive." Maybe I am ridiculous, but to me (and my opinion is but a grain of salt) unspeakable loses me because it could be anything, when what I want is simplicity and a logline that is upfront.

WONDERFUL LOGLINE!!!