After Rainbow Dash makes Twilight chuck a potion that she doesn't know does, and it ends up in the water, things get a little sickening. At first. After passing out, turning into cats, separating, and getting taken into the clans. The leaders are impressed by the abilities of these 'cats' and want them to join.

Especially Blackstar, leader of ShadowClan. What does he want them so badly for?