His Secret Christmas Baby - Rita Herron (HI #1174 - Dec 2009)

Series: Guardian Angel Investigations (Book 2) 

THIS CHRISTMAS HE RECEIVED THE GREATEST GIFT OF ALL...AND TACKLED THE MOST CRUCIAL CASE OF HIS CAREER

Investigator Derrick McKinney's quiet bachelor life was shattered when the son he just learned existed was abducted right out from under the watchful eye of his beautiful guardian. And although she was left unconscious and heartbroken, someone feared Brianna Honeycutt saw more than she claimed, placing her life in danger. Working together, Derrick now had to push aside the long-buried attraction he'd always felt for Brianna. More determined than ever to end this nightmare and put a smile back on Brianna's face, Derrick vowed he'd stop at nothing to bring his baby home in time for Christmas.. 

Very good book.  Derrick had returned to Sanctuary to take a job with Guardian Angel Investigations.  Almost as soon as he arrived, he discovered that he was the father of a baby boy, then that baby was kidnapped.   Brianna was injured and heartbroken.  As she and Derrick investigated the kidnapping it became apparent that there was more behind it than they had thought.  Besides his need to get the baby back, Derrick finds himself attracted more and more to Brianna.  I really liked both Brianna and Derrick.  Brianna had been a very good friend to Natalie, the baby's mother.  When Natalie begged Brianna to take care of Ryan if something happened to her, Brianna could do nothing less.  When Derrick came back to Sanctuary she suspected that he was Ryan's father and was afraid that she would lose Ryan to him.  She also realized that the crush she'd had on Derrick while a teenager had never gone away.  All the while they were searching for Ryan she kept picturing the three of them as a family.  Derrick had had an abusive father and had not planned to ever have children, being afraid of turning out like his father.  But as soon as he knew about Ryan, he knew that he wanted to be the best dad he could.  He did have some issues with Natalie and Brianna not telling him about the baby, fearing it was because they didn't consider him fit to be a father.  He had noticed Brianna when they were in school, but considered her far too good for him.  Now he had a chance to have it all.  I liked the way that they were able to work together to solve the mystery of why Ryan was kidnapped.  I also liked that they were eventually able to overcome their issues with each other and get their happily ever after.