Not her Baby (Rocky Mountain Home Series, #3‪)‬

Cassie and Chrissy were closer than any two sisters could be, especially since their parents passed away.  Chrissy's husband was an FBI agent, named Adam, who also thought of Cassie as his sister.  Chrissy and Adam wanted a baby more than anything in this world and were devastated when they found out Chrissy could not conceive.  After much soul searching and discussions, Cassie became their surrogate.  But as fate would have it, on the day the doctors confirmed Cassie's pregnancy, the three are in a terrible car accident.  Chrissy and Adam did not survive.  Adam's FBI partner and best friend, Drake, promises to be there for Cassie through her grief and pregnancy.  After the second attack on Cassie and the near miscarriage of the baby she carries, Drake rushes to solve the answers to Chrissy and Adam's murder and also protect the woman he has come to love and the baby that grows inside her.