Complex sentence: Frank snaps and returns to Bettencourt's residence with vengeance and dispatches several of his henchmen after which he steals a car to get away, only to find "the package" tied to a chair in the back seat.
Split into simpler sentences: Frank snaps and returns to Bettencourt's residence with vengeance and dispatches several of his henchmen. After which, he steals a car to get away, only to find "the package" tied to a chair in the back seat.