Warrior Cats The Broken Code Series Books 1 - 6 Series 7 Collection Set By Erin Hunter:

Lost Stars:
For the first time, all five warrior Clans have settled into their true homes in the territory around the lake. But when a shockingly harsh leaf-bare season descends on the forest, a new darkness begins to spread—a shadow that threatens a beloved Clan leader, the cats’ connection with their ancestors in StarClan, and the very warrior code they live by.

The Silent Thaw:
ThunderClan’s leader, Bramblestar, has been behaving erratically after losing one of his nine lives, and suspicion is quickly spreading across Clan borders. And when a strange apparition sparks unrest in SkyClan and ShadowClan, each warrior must decide.

Veil of Shadows:
After losing one of his nine lives, ThunderClan’s leader, Bramblestar, became intent on rooting out and exiling cats he claims are traitors to the warrior code. But some cats know the truth: this isn’t the real Bramblestar, and their leader’s true spirit.

Darkness Within:
Exiled after a battle that left all five Clans devastated, ThunderClan’s loyal deputy, Squirrelflight, must bring to light an earth-shattering truth: the identity of the cat ruling ThunderClan while wearing Bramblestar’s face.

The Place of No Stars:
The time has come to return to the Dark Forest.ThunderClan’s deputy, Squirreflight, has vanished with the cat now known to be an impostor, sowing suspicion and mistrust among the five Clans.

A Light in the Mist:
When fear reigns supreme, only hope can save the Clans.The impostor’s reign of terror has brought the Clans to the brink of destruction, and now, every warrior—living and dead—must unite to defeat him before he delivers his final blow.