ThunderClan cats

It has been a while since the Clans won the battle against the Dark Forest. ThunderClan is prospering under Bramblestar's leadership and the rest of the Clans have been thriving too. But a strange black liquid is covering ShadowClan's territory, killing and poisoning their prey, and ShadowClan's leader, Blackstar, decides to steal prey from ThunderClan to keep his Clan from starving. Bramblestar originally intended to attack ShadowClan, but his sister, who had fled from the ShadowClan camp when she heard that Blackstar intended to steal ThunderClan's prey, begged him not to attack them. As ShadowClan keeps pushing farther past the boundaries, will Bramblestar chooose loyalty to his sister or loyalty to his Clan?