Scar Night - Alan Campbell

Suspended by chains over a seemingly bottomless abyss, the ancient city of Deepgate
is home to a young angel, an assassin, and a psychotic murderer hungry for revenge-or
redemption. But soon a shocking betrayal will unite all three in a desperate quest. . . .

The last of his line, Dill is descended from legendary Battle-archons who once defended
the city. Forbidden to fly and untrained even to wield the great sword inherited
from his forebears, he has become a figurehead for a dying tradition. Now he lives
a sheltered existence in one of Deepgate's crumbling temple spires under the watchful
eye of the Presbyter who rules the city.

Spine assassin Rachel Hael has better things
to do than oversee the Presbyter's angel. Each dark moon she must fight for her life
among the city chains, hunting an immortal predator with a taste for blood.

But
when a traitor brings enemies to Deepgate's doorstep, Dill and Rachel are forced
into an uneasy alliance with the city's oldest and most dangerous foe. They must
journey down into the uncharted chasm to save their sprawling metropolis-and themselves-from
annihilation. Once they descend however, they learn that what lies below is far more
sinister than what they've been taught to expect.