One Minus Zero

Gemma wakes up with a brutal hangover, a missing memory, and Maeve—a striking redhead she can barely remember picking up. But as an unnatural, bone-chilling frost spreads through her Wellington flat, Gemma realizes Maeve isn't just a morning-after regret.
While her flatmate lies on an operating table fighting for her life, Maeve presents Gemma with a terrifying piece of arithmetic: for one heart to keep beating, another must stop. As the temperature drops and her world begins to warp into something ancient and nightmarish, Gemma is forced to navigate a horrifying choice before the math settles itself.