The following article contains an answer for the question: Who portrays Dr. Jennings' daughter? , can you please find it? 

Joe Hickey, his wife Cheryl and his cousin Marvin have developed a money-making scheme – they kidnap the child of rich parents, hold the child for 24 hours and demand ransom money from the father. They each have a specific role in the operation – Marvin kidnaps the child, Joe stays in the victims' house to control the mother, and Cheryl deals with the father. 
Dr. Will Jennings is a research physician who has just had his big career break by patenting a new anesthetic drug. His wife, Karen Jennings, who was previously a nurse, is a stay-at-home mother to their daughter Abigail, aka Abby (Dakota Fanning). Joe targets Abigail as the next kidnapping victim and the trio begin to enact their usual plan.
Abby is kidnapped by Joe and Marvin and they soon discover that she has asthma and is dependent on an inhaler pump. Marvin takes Abby to his cabin and Joe holds Karen hostage. Cheryl keeps Will at gunpoint and informs him of his daughter's kidnapping. It is subsequently revealed that Cheryl and Joe kidnapped Abby because they believe that Will is responsible for the recent death of their daughter Katie: Katie had a tumor and died while being operated on by Will. Will reveals that Katie died because of unforeseen bleeding accidentally caused by the head surgeon during the operation; the surgeon then lied to Joe and Cheryl, convincing them that Katie's death was as a result of negligence by Will in Katie's recovery to avoid scrutiny by them. It is revealed that Joe's real plan is not to let Abby go home after the ransom is paid, but rather, to keep her and raise her as his own daughter.

Dakota Fanning