Dr. Abigail Chase is the deuteragonist and love interest of Benjamin Franklin Gates from the National Treasure and National Treasure 2: Book of Secrets. In both films, she is played Diane Kruger.
She is first seen with the FBI while Ben and Riley are stealing the Declaration from Ian. Ben sends Abigail one of George Washington's original campaign buttons that are coated with invisible ink that will mark the keys. That night at the gala, Ben disguises himself as a janitor to use Abigail's fingerprint from a champagne glass. She was kidnapped by Ian and his men while she follows Ben outside. During the chase, Ben rescues her from Ian and shows her that he has the replica. Abigail decies to join Ben and Riley on the case, but Ben is captured by FBI agent Peter Sadusky. The three head to New York City as Ben escapes by jumping overboard. Ian returns the Declaration and pipe as promised as Ian reveals that he has captured Patrick. At the bottom of the shaft, they find a room lit by a lantern as Ben and Patrick use to convince Ian that it signifies Paul Revere's Ride. As Abigail, Ben, Riley and Patrick are stranded as they ascend to the surface. Ben pushes a buttom engraved on the wall of the "unfinished pyramid the all-seeing eye". The four escape and the FBI arrest Ian and his men. Abigail begins to have romantic feelings for Ben as Ben also begins to have romantic feelings for her too after Riley drives away in his car. Abigail gives Ben a map to the mansion and the two run off.
National Treasure 2: Book of Secrets
She and Ben investigate the book of secrets as they discover the cipher on the diary page. She and Ben head to London to investigate. Ben discovers that Patrick has sent Abigail to help. She and the group manipulate events to assure that the President's birthday celebration occurs at Mount Vernon which allows Ben to sneak in and lure the President alone to set of disused tunnels. She, Ben and Riley locate the Book in 1924 and destroyed it after taking a photo (which is still in the book). She, and the group arrive at Mount Rushmore, prepared to deal with Mitch, but Mitch has brought Emily along as a hostage. After Mitch tries to kill Abigail, Mitch finds out that the door is open and Ben and the others flee. Ben is cleared of kidnapping the president himself. In the end, Ben and Abigail reconcile their relationship as they both have romantic feelings once again towards the end of the film.