At the first meeting of the [Slug Club], [Harry] sits nervously through a long, forced conversation with [Professor Slughorn] and various other students.
[Harry], [Ginny], and [Neville] leave [Slughorn]'s compartment, discussing the [Slug Club].
In the Slytherins' Compartment
[Harry] dons his [Invisibility Cloak] and follows [Blaise Zabini] into [Draco Malfoy]'s compartment.
[Harry] overhears [Malfoy], [Blaise Zabini], and [Pansy Parkinson] talking about the [Slug Club].
[Malfoy] hints to his friends from [Slytherin] that he is working for [Voldemort] - with [Harry] listening in under his [Invisibility Cloak].
[Malfoy], left alone in his train compartment with an invisible [Harry], performs the [Petrificus Totalus] on him, leaving him hidden and unable to move as the [Hogwarts Express] clears.
Chapter 8 - "Snape Victorious" - In which Tonks rescues Harry from the train and Snape leads Harry in to the feast, criticizing Harry all the way. Once inside, Harry discusses his status as 'The Chosen One' with those around him and Dumbledore gives his opening speech, announcing that Slughorn will be teaching Potions and Snape teaching Defense Against the Dark Arts. On the way out of the hall, Harry and Ron discuss Malfoy and run into Hagrid, who tells them about Grawp and leaves them feeling guilty for not taking his class.
Tonks to the Rescue
[Harry] lies alone on the floor of the [Hogwarts Express], [Petrified] and invisible, thinking about how to get out of his predicament.
[Tonks] arrives, throws off [Harry]'s [Invisibility Cloak], and unfreezes him - they then jump from the [Hogwarts Express] and wait at the gates of [Hogwarts] for someone to arrive and let [Harry] in.
Late to the Welcoming Feast
[Snape] arrives to fetch [Harry], criticizes [Tonks], and goads [Harry] all the way up to the castle, taking off points for his lateness.