Into the Fire by Irene Hannon

As a former smokejumper, arson investigator Bri Tucker knows her way around fires. But after a mysterious blaze takes the life of a former colleague, Bri inherits a curious puzzle from him that raises questions about several fiery deaths. Someone, however, doesn’t want her picking up where he left off in search of answers.
When she teams up with ATF Special Agent Marc Davis to solve the puzzle, the danger escalates. But will they manage to track down the person behind the mysterious deaths before their budding romance–and maybe even their lives–go up in flames?

The bestselling and award-winning queen of romantic suspense is back with a brand-new series that is sure to get your adrenaline pumping as you burn through the pages to discover the truth.