Maverick's Surprise Son by Christine Rimmer

After a deathbed promise, a cowboy makes a life-changing decision.

Overnight, rancher Jace Abernathy has gone from carefree bachelor to single dad. Frankie isn’t really his, but nothing will prevent him from protecting the orphaned newborn he saved from a fire, not even nurse Tamara Hanson. Tamara, who lives her life by the book, is convinced Jace is unprepared for fatherhood. Jace believes rules sometimes need to be broken. What neither of them realises is that what they need most of all...is each other.