After hearing Buckbeak's execution, the trio get caught up in shenanigans between Scabbers, Crookshanks, and the Grim! The Grim drags Ron through a tunnel underneath the Whomping Willow and Harry and Hermione give pursuit. The twists and turns of the tunnel are nothing compared to what we all find out at the end of the tunnel, in the Shrieking Shack!