An Agent for Arabella - Pinkerton Matchmakers, #17

Arabella needs a job to pay for her sister's medical care at the sanatorium in Denver. After hiring Pinkerton agents to help her rescue her sister, she goes to the Pinkerton Headquarters for a job and is hired easily enough. Then, she sees that she is paired with Gerard Fletcher. Worse, the agency marries her to the man and sends her on a case with him. Gerard Fletcher decides since his success with rescuing the mail-order brides from a Mexican brothel, he goes to the Pinkerton Headquarters in Denver for a job and is quickly hired.
Then he sees Arabella and they are married. Great. She's beautiful, even if she does have an attitude. Then he gets the case, and his world crumbles. He's sent after his old partner to catch him in a swindle. Great. The very man that Gerard swindled and owes money to. Love Never Fails, even as Gerard and Arabella do in this sweet romance.