An Agent for Brielle - Pinkerton Matchmakers, #18

A beautiful mathematician, a politician, and a murder case that isn't what it appears to be... Brielle Bradford arrives in Denver, Colorado for one purpose: end her two-year engagement to the prominent politician Matthias Blackburn. What she discovers is that Matthias has put away his political aspirations to fight crime the Pinkerton way. Still reeling from the news, she is enlisted as a temporary agent in order help solve a murder case.
The only problem: she has to marry Matthias. Matthais has never gotten over Brielle's betrayal. Her reluctance to be his wife baffles him when he knows she loves him as much as he loves her. Yet, marriage to Brielle is what he wants and he'll take it anyway he can, even if its a marriage of convenience for the sake of a murder case. Further testing the couple is a suspect whose enigmatic intelligence and attractiveness lures Brielle away from the case.
But Matthias won't give up until they find their suspect and nor will he give up Brielle without a fight.