Back in Gryffindor Tower, Harry realizes the urgency of stopping Voldemort and explains the situation to Ron and Hermione. He then goes to bed, unexpectedly finding his Invisibility Cloak back in his bed.
Detention in the Forbidden Forest
Firenze invites Harry to ride him to safety, infuriating Bane. He takes him to Hagrid, however, explaining unicorns and [unicorn blood] - and Voldemort's desire for the [Philospher's Stone] - to Harry along the way.
Chapter 16 - "Through the Trapdoor" - In which the students begin their exams, Hagrid lets slip how to control Fluffy, HRH try to warn Dumbledore but he has been summoned away. Fearful that Snape is about to make his move to get the Philosopher's Stone, HRH decide to go after it themselves. Under Harry's invisibility cloak they make their way to Fluffy, put him to sleep, and go through the trapdoor, past plants, chessmen, and potions.
Exams and Other Worries