Desperate to repair and reunite his dysfunctional family, an idealistic young man brings them to an abandoned island mansion in an attempt to relive his nostalgic childhood vacations, only to discover it overrun by giant carnivorous slugs. (HORROR-COMEDY)
I have to admit, I love the “…carnivorous slugs…” – it’s weird and original. Find a better description for the MC “…idealistic young man…” means very little in a logline. Give him a genuine flaw and preferably relevant profession such as; arrogant family psychologist.
If his goal is to reunite the family, make the inciting incident something that relates directly to that. How about; after his parents divorce or after his estranged father returns home.
I think this has potential, and with a few changes, the logline could read very well.