Against This Vast Army — Mark Allyn Stewart

At the turn of the century, Manhattan is plagued by the arrival of a fearsome master vampire and the only person who can oppose him, a vampire hunter's apprentice named David, will discover that behind this vampire's power is a dark secret that could make the fiend impossible to destroy.

Stranded in New York with no hope of reinforcements, David has little choice but to rely on his skill, his wits, and Sharon, a beat cop who has discovered that vampires are very, very real.