I missed part of it, tell me what happened

Nothing much (if this is what you are asking ;-) ). After the sleepover they got together at the same place again when the boy's divorced biological father was dining out with his girlfriend. The kids have had the usual kid's fun, then they decided to make a bubbly (not bath - drink) out of beer or something (I was not keeping my eye on it, too). By that time the girl's mother, having tried to call and to check on her daughter, found out that the phone and therefore the place of the night venue her daughter provided her were bogus. Immediate red alert to all the former and current spouses and lovers was issued. This is how they all got into that apartment just in time before anything, if any, could have happened.