Connor File - The Rider Files, #5.5

Rick Swanson loves his job as a firefighter, and when the intriguing ER doctor, Mackenzie Connor, catches his eye, the temperature rises. But his world is sent on a tailspin when an arsonist has an agenda of revenge. Rick needs to deal with this threat if he's going to get his life back on track.  Mackenzie Connor is falling fast for fireman Rick, until he inexplicably distances himself. When she learns he's trying to protect her from a crazed arsonist, she won't be idle.
And she won't back down from danger. She enlists the help of the elite Rider Security and Investigation team, but can she reach Rick in time to save him?  **If you like action, adventure, and strong female leads, this is the series for you. The romance is medium with heat with some explicit language. Each novel shares characters, but they are also their own stand-alone happily-ever-after. This novella can be read in any order in the series.