Snape had actually set them a potions logic puzzle. Tris had to hand it to these wizards-they really knew how to entertain themselves, coming up with something like this.
What surprised him was that Hermione solved the logic puzzle in under a minute, picking out the two correct bottles from seven of varying shapes and sizes.
One would let them move forward through the black flames, while the other would let them return through the purple flames.
There was a problem, though: each potion amounted to a single small sip, enough for only one person. In other words, if they used the potions, only one person could go forward and one could go back. The other two would be left here.
"Why would he do that? Snape is such a pain." Ron sounded annoyed at first, then hesitated. "But if there's only one dose, how did he get through?"
"He set up this obstacle. Of course he could get through. All he had to do was prepare an extra dose beforehand," Hermione said.
"That doesn't make sense." Ron shook his head. "It's his own obstacle. Why would he need to prepare a separate dose? He knows which potion he needs. He could just pick it up and drink it."
That gave Hermione pause, but she quickly shook her head. "Then perhaps he knows how to get through the flames he set up. This isn't the time to worry about that. What matters now is how we divide up the potions.
"Who goes in, who goes back, and who waits here?"
They hesitated.
Harry, Ron, and Hermione all thought that Tris was the best at magic among them, so sending him ahead should give them the best chance of stopping Snape.
But after coming this far, the thought of not being