Gwen whacking one of Finney’s bullies over the head with a rock when he’s getting beaten up. She gets hit too but she still charged in to defend her older brother.
Thanks to a combination of all the tips the ghost boys provided him, especially Robin's reassurance, Finney stands up to the Grabber by hitting him with the dirt-filled black phone and improvising the cable, hole in the floor, and window bars from earlier into a pitfall trap. This incapacitates him long enough for Finney to start strangling him with the telephone cord. Just before the Grabber dies, however, the phone rings one last time. But not for Finney; for the Grabber. Finney then puts the phone up to the Grabber’s ear, ensuring the last thing he hears is his previous victims taunting him about his impending demise.
Finney:It's for you.(puts the phone up to the Grabber's ear)
Vance: Welcome to the nightmare end of your pathetic little life!
Griffin: (laughing) You don't have much time!
Vance: Today's the day, motherfucker!
Robin: I can't kill you, you hijo de puta, so Finn is gonna to do it for me!
