Hearts Under Siege by Natalie J. Damschroder
Brady Fitzpatrick has spent a decade burying the pain of a broken heart while working for SIEGE, an information-gathering spy agency. That it kept him away from his family as well as his best friend Molly has been an unfortunate side effect. But when his brother, also an agent, is killed during a foreign op, Brady is drawn into a web of intrigue that threatens the lives of everyone he loves…
Molly Byrnes has loved Brady forever. As his best friend and a de facto member of the Fitzpatrick family, she holds them together in their crushing grief. But as a member SIEGE's ground team, she doesn't buy the official line about Brady's brother's "accidental" death and launches her own investigation—only to uncover a shocking secret that she and Brady must get to the bottom of before their target finds them.
Tangled emotions land them in bed together, opening Brady's eyes to the incredible, fearless woman who's been there for him all his life. But after a lifetime of disappointment, how can Molly trust the possibility of a future with him…or if they can count on any future at all?