Mithril sends in Sousuke's team to Hong Kong in order to stop an AS that is attacking the city indiscriminately.  Melissa and Sousuke do recon together but Sousuke is so far out of it that he runs a red light and has a wreck.  That's about the time the AS shows up.  Later, Melissa tells Sousuke to get out of the van or get his head in the game.  He chooses the option she thought was impossible - he leaves.