This Savage Song (Monsters of Verity, #1) by V.E Schwab

Kate Harker and August Flynn's families rule opposite ends of Verity, a grisly metropolis where violent acts summon real monsters. The truce that keeps the Families at peace is crumbling, and August is sent to spy on Kate. But when Harker's men try to kill her and pin it on the Flynns, August and Kate find themselves running from both sides.

Kate Harker and August Flynn are the heirs to a divided city, a grisly metropolis where the violence has begun to create real and deadly monsters.

All Kate wants is to be as ruthless as her father, who lets the monsters roam free and makes the inhabitants pay for his protection.

August just wants to be human, as good-hearted as his own father-but his curse is to be what the humans fear.

The thin truce that keeps the Harker and Flynn families at peace is crumbling, and an assassination attempt forces Kate and August into a tenuous alliance.

But how long will they survive in a city where no one is safe and monsters are real