Unstoppable — Cindy Skaggs

Bad boy Mick Donovan has dedicated his life to avenging his brother's death, even aligning himself with an FBI Task Force to achieve his ends. Which leads him to the mess he's in now--undercover as the husband of the woman he's been fantasizing about, despite knowing how off-limits she is, to protect an innocent child.

After an ambush, Destiny Harper is on the run and out of places to hide from a ruthless drug lord hellbent on claiming his son. Charged with protecting the boy, Dez lands in the mountains on a collision course with Mick, a blizzard, and a past she'd rather forget. But even as the close quarters ignites the passion between her and the sexy biker, she knows there's no future with him. Mick will sacrifice everything for revenge -- even her.

The Untouchable series is best enjoyed in order:
Book #1 Untouchable
Book #2 An Untouchable Christmas, novella
Book #3 Unforgettable
Book #4 Unstoppable