WHN is a tragedy and won't end on a good note.
The characters will not learn from their actions, and Griffin's victims will never be able to fully recover from the murder or receive the proper amount of closure necessary to move on with their lives. We will get a chapter from Griffin's POV.
Possibly the last one. Claire has made another suicide attempt.
Claire has disappeared because she made another suicide attempt (probably successful this time) in an attempt to get Milo and Griffin hit with felony murder
charges, so they'll spend the rest of their lives in prison. Hailey's Law likely contains some provision that was necessary for this.