Felix and the Spy - Scions of the Underworld, #4

Bridgerton meets You've Got Mail in this spicy age gap fantasy romance novella that tells the story of a feisty spy and her gentle boss who share a secret pen friend relationship. Felix, the head of the Inferno's secret service, has been lonely since his wife's death. Intrigued by a new pen friends program, he begins corresponding with a mysterious war widow. Through the letters they share, he develops a deep bond with her.
But when she asks to meet, Felix is in for a huge surprise. Amara hasn't been the same since her mother's death. Crumbling under the shadow of grief, she has become volatile and withdrawn. So, when Mr. Garrett, a lonely widower begins writing to her, she finds solace in a kindred soul. With every letter, she opens up more and more. Until she discovers that Mr. Garrett is Felix, her boss. Struggling to maintain a professional relationship amidst their growing attraction, Felix and Amara embark on a secret love affair.
But as they spend more time together, they realize that love sometimes blooms in the darkest and most unexpected places.