Isaac’s dad is killed.  We later find out that it was a new lizard like creature that came after Allison.  Scott escaped from where he was hiding during the full moon to save her.  Because the cops thought Isaac killed his dad, they locked him up for the night.  Stiles and Derek went to get him out so that he wouldn’t turn in jail, but it was too late.  Meanwhile, Jackson attempted to film himself turning, but the video tape showed that nothing happened to him during the full moon.