Grace and Glory (The Harbinger Series, Book 3) by Jennifer L. Armentrout

In the climactic conclusion of Jennifer L. Armentrout's Harbinger trilogy, the stakes soar to unimaginable heights as danger, betrayal, and forbidden love collide in a battle for the fate of existence itself.

Trinity Marrow, reeling from loss and shattered by the death of her beloved Protector, finds herself at the mercy of insurmountable odds. Despite alliances forged with demons and Wardens alike, victory against the formidable Harbinger appears increasingly elusive.

Desperate times call for desperate measures, and the unthinkable becomes their last resort: to summon Lucifer, the ultimate fallen angel, back into the world. With no other options left, they gamble everything on the hope that his unparalleled power can tip the scales in their favor.

Yet as Trin and Zayne navigate treacherous new alliances and tenuous bonds, Lucifer's return unleashes chaos of apocalyptic proportions. Hellfire rages across the earth, threatening to consume all in its wake, as the very fabric of reality hangs in the balance.

In the crucible of impending doom, Trin and Zayne find themselves bound by a perilous and forbidden connection, their destinies intertwined as they confront the harrowing consequences of their choices.

As the apocalypse looms ever closer, uncertainty shrouds the outcome, and the world teeters on the precipice of oblivion. Win or lose, triumph or tragedy, one certainty remains: the aftermath will reshape the world irrevocably, leaving nothing untouched and everything forever changed.