End Of Days by Susan Ee

In a world ravaged by angelic warfare, a determined young woman named Penryn embarks on a perilous journey to rescue her sister from the clutches of a malevolent angel. As she navigates the treacherous landscape of a post-apocalyptic Earth, Penryn forms an unlikely alliance with Raffe, a fallen angel with his own agenda. Together, they confront formidable foes, unravel celestial mysteries, and grapple with the complexities of trust and sacrifice. Amidst the chaos, Penryn discovers her own strength and the power of hope in the face of seemingly insurmountable odds.