In the last part they all end up in Freddie's shed, Cook sees some guy behind the gate when he's in the garden and hides in the bush. The guy walks closer and it's John Foster. A scene or two later we see Cook climbing into some room, and it becomes clear that it's Foster's house. There's lots of plastic boxes and in them are Freddie's clothes covered in blood etc. Suddely in the background we hear something like "what are you doing?", and Foster's there with a bat. He tells Cook to get on his knees because he 'deserves' Effy, but he doesn't. And then the **** ending happens. So basically only Cook knows what happened.