A Thief in ThunderClan (Warriors, Volume 4)

ThunderClan is still reeling from Tigerstar's many betrayals, and no cat more so than Brightheart. Her wounds may have healed, but becoming a warrior again hasn't helped her lingering suspicions about where her Clanmates' loyalties lie--so when fresh-kill starts going missing from camp, she fears the worst.

Alongside her mate, Cloudtail, Brightheart decides to investigate without alerting the other warriors. StarClan alone knows who else she can trust, and Firestar is consumed with problems of his own. But as Brightheart struggles to untangle the origins of the threat within their camp, she'll have to take a leap of faith and work together with the other cats--and prove she remembers what it really means to be part of a Clan.