Limelight (Arcane Casebook)

When a madman starts robbing banks the really old-fashioned way — by blowing holes in them with magical explosives — the police turn to Alex Lockerby to catch him before he kills again.
There are two problems: first, as far as Alex knows there’s no such thing as a blasting rune. And second, his friend Danny Pak is up for a promotion, and this isn’t Danny’s case.
Alex splits his time between chasing the homicidal bomber and helping Danny investigate a dead writer whose novel was based on Broadway’s most famous unsolved murder.