Trial by Fire by DiAnn Mills

A new standalone novella from one of the top names in romantic suspense. Includes a preview of the first book in DiAnn's explosive new FBI Task Force series!
Special Agent Savannah Barrett and her partner, SA Paul Winston, have been investigating a puzzling string of church arsons when she receives devastating news: her estranged son has been killed in a car accident, leaving Savannah sole custody of three young grandchildren she didn't know existed. As she and Paul investigate new fires, trying to establish an M.O. and a suspect list, Savannah is thrown back into parenting while trying to handle her own heartbreak. Paul becomes her biggest support-on and off the job-kindling the fire between them.
But when the case takes a personal turn and Savannah's grandkids are threatened, she and Paul must put everything on hold to stop this arsonist's reign of fire.