Here's my take on it in summary (but I could be wrong in some places so don't yell at me if you disagree):
I: This young guy lives in an abusive family so he runs away. He meets another runaway and they get along great but then they start playing this game where they have to keep trying more dangerous things until the friend dies (by hanging). The first guy misses him, regrets it all, and tries to drown himself but fails. At the end he goes back to check on where he came from but everyone is gone.
Nightfall Overture: He's been roaming around all this time and when he's walking around one night in the winter he starts hearing voices and nearly ends up falling asleep outside and freezing to death. A woman saves him and he wants to stay with her, but he's drawn back out to confront the voices. The voices are his old friend somehow contacting him from the other side, and he wants revenge. The friend takes over control of his body, takes him back to the tree where he was hung, and forces the main guy to hang himself so the friend can take over his body.
Closing Chronicles: The friend has got the main character's bpdy now, while the main guy is off in space, hoping tobe reincarnated. The friend isn't really happy now that he's back. The woman misses the main character, and when his friend shows up she knows he's not the right person inside. But she seduces his hoping that the main guy will be reborn inside her. At the end that's what happens, and the friend says he's going to return to the shadows or something like that.
I'm sure if I took a little more time I could do a better job, but I hope that helps.
