Abigail Chase is the deuteragonist of the National Treasure series. She is an archivist at the National Archives and also helped find two of the most famous treasures of all time, the Templar Treasure and the Lost City of Gold. She is also the love interest of Ben Gates.
Not much is known about her early life. She was born in Germany in 1976 but immigrated with her parents when she was a child. Sometime before 2004, Abigail took the job of an archivist at the National Archives in Washington, D.C. as of at least 2004. As a hobby, Chase collects vintage campaign buttons. She appears to have an ex-boyfriend, who she dislikes, named Stan.
She was told by Ben Franklin Gates (posing as Paul Brown) and Riley Poole that the Declaration of Independence will be stolen by an Ian Howe with whom both of them worked. Supposedly, there is a treasure map in invisible ink on the back of the Declaration. Abigail was initially incredulous of the map's existence, but is eventually drawn into a treasure hunt going from D.C. to Philadelphia to New York City. A few nights later when she seems to look as if she was in on the theft in the first place. She is rescued by Gates and Poole from Ian Howe when Ian tries to grab the document and from then on she is thrown into the drama.
After finding out where the next clue is at Ben's father's house in Philadelphia. The clues lead the three to The Silence Dogood letters in Philadelphia and then to the Liberty Bell and Centennial Bell, where Ian catches up with them. Ben and his friends are unable to successfully outsmart Ian and he takes the Declaration. Riley and Abigail make a deal with Ian to tell him what the final clue so that they won't turn Ben over to the police. The final clue is at Trinity Church where Ben is given a choice to whether to save her or the Declaration. He chose to save the Declaration and she agrees with him. They eventually trick Ian into believing that the treasure is not there but in Boston. Afterwords they find the treasure and make a deal with the FBI whereby Abigail's record is cleared and Ian and his henchmen are the only ones to go to jail. At the end of the movie it's clear that Ben and Abigail are in a serious romantic relationship.
Book of Secrets
As of the spring of 2007 Abigail and Ben are in the midst of breaking up when Ben and Riley Poole show up at the home she and Ben used to share looking for a document with a cipher on it that could help Ben prove Thomas Gates was not part of the Lincoln Assassination. They are on the outs because Ben always has to have the last word on anything. Abigail comes home early with her date and discovers Ben and Riley and wants the two of them to leave. After another argument with Ben, Abigail lets them see the documents. She meets with Mitchell Wilkinson the next evening about the so-called missing diary page and is called by Ben asking if they and Abigail can help with another cipher involving Edouard Laboulaye which Abigail refuses. Abigail decides a few days later to go to find Ben in London England at Buckingham Palace. The two set up an argument so that they could be arrested. While arrested they sneak into the Queen's private study and check one of the twin Resolute Desk. They discover a wood carving. However the two have also been discovered to have escaped. Riley, who first guided them into the office guides them out. However Mitchell Wilkinson is outside the palace. Ben takes a photo of the carving and throws it in the Thames River.
Back in the United States the carvings are found out to be pre-Colombian American era (pre-1492) and then Ben and Abigail reason that the best person who can help them figure it out is Ben's mother Emily Appleton Gates. The two along with a reluctant Riley and Patrick go to see her at the University of Maryland in College Park Maryland, where she is a Native American languages professor.
When Emily tells the three that it is only half a map, Ben says that the other is in The Oval office. During the Easter Egg roll, Abigail and Ben go to the White House and she gets her new boyfriend to show them inside the office. There Abigail drops an earring as a distraction so that Ben can search the desk. The two carvings are not a map to a treasure but another clue. Riley Poole says and that clue is in the President's Book of Secrets.
Ben gets the wild idea to 'kidnap' the United States President during his birthday party at Mount Vernon. Abigail tries to talk him out of it but there is no stopping him.
She meets up with Ben and Riley at the Library of Congress where they find the Book of Secrets. The book's description of the wooden planks leads them to Mount Rushmore.
Wilkinson tries several times to coerce the group to do things his way and even goes so far as to threaten Abigail with a knife. After their escape from Cibola, Abigail takes Ben back. She shared a kiss with Ben towards the end of the film.