Harrington, Anna (Romance fiction writer). Lords of the armory

Series information from author's website

Soldier turned solicitor Lord Merritt Rivers has dedicated his life to upholding the law. He patrols the streets faithfully, hoping to stop crimes before they can happen. While hunting an escaped convict, he encounters a woman also hunting thieves. She's a delicious distraction, until he discovers that she is the criminal he's after. She's smart, challenging, and everything he finds attractive, but he cannot trust her. Veronica Chase has hidden her past as a nobleman's daughter. She confesses to a crime to keep her adopted brother out of prison. She now lives in London's underworld, trapped between worlds, belonging nowhere. Forming an uneasy alliance, Veronica and Merritt work together to protect innocent Londoners during the city's riots. Moving between her world and his, they grow closer to each other and to the mob's dangerous leaders. But their newfound trust won't be enough, until each face their demons and ask what's worth saving--the lives they've chosen to lead or the love that leaves them yearning for more