Firenze suddenly reared on to his hind legs in anger, so that Harry had to grab his shoulders to stay on.

"Do you not see that unicorn?" Firenze bellowed at Bane. "Do you not understand why it was killed? Or have the planets not let you in on that secret? I set myself against what is lurking in this forest, Bane, yes, with humans alongside me if I must."

And Firenze whisked around; with Harry clutching on as best he could, they plunged off into the trees, leaving Ronan and Bane behind them.

Harry didn't have a clue what was going on.

"Why's Bane so angry?" he asked. "What was that thing you saved me from, anyway?"

Firenze slowed to a walk, warned Harry to keep his head bowed in case of low-hanging branches, but did not answer Harry's question. They made their way through the trees in silence for so long that Harry thought Firenze didn't want to talk to him anymore. They were passing through a particularly dense patch of trees, however, when Firenze suddenly stopped.

"Harry Potter, do you know what unicorn blood is used — for?"

"No," said Harry, startled by the odd question. "We've only used the horn and tail hair in Potions."