Olivia Behan Cahill
Age:Unknown (deceased) ?-1526?
Relationships:Gideon Cahill, Luke Cahill, Katherine Cahill, Thomas Cahill, Jane Cahill, Madeleine Cahill
First Appears In:Vespers Rising
Last Appears In:Vespers Rising

Olivia Behan Cahill was the widow of Gideon Cahill. She was one of the first Cahills. She was the one to start developing a Serum Antidote.


Olivia Behan Cahill married Gideon Cahill and had five children (Madeleine was born after Gideon died). Her home was destroyed and her husband was killed in an explosion that Gideon set to stop Damien Vesper from getting his research. She was pregnant with her fifth child, Madeleine, at the time. Her four oldest children were scattered around the globe, and she taught Madeleine that reuniting the family was the most important thing. In 1526, Olivia died, according to the book Vespers Rising. However in the book Into the Gauntlet, at the end of the clue hunt the Cahills find a record from Olivia Cahill's original accounts that describes her desire for the family to be re-united and suggests that Olivia Cahill survived for long enough to hear back from Madeleine of her children's deaths.

Olivia taught Madeleine all the skills of the other four founders. Every time Madeleine does well she uses one of these expressions to praise Madeleine:

a jot of Jane - praising an artistic accomplishment

a cut of Katherine - to praise an intellectual victory

a touch of Thomas - praising an athletic achievement

a lick of Luke - to praise a strategic success

magnificence of Madeleine- if something else was done well


Into the Gauntlet

Within the Madrigal Stronghold on Cahill Island the Cahills find a translation from Olivia Cahill's accounts. In it, Olivia Cahill reminisces on happy times with her family around the dining table prior to the fire of 1507, and discusses her hopes for family reunification. In a later entry she notes that Madeleine has brought her news of her childrens' deaths around the globe. She discusses her fear that her family will unleash devastation on the world at large, and her hope that one day descendants from each branch of the Cahill family will meet at the table and the Cahill family will be at peace.

Vespers Rising

Part One - Gideon Cahill

Olivia is first shown washing the kitchen table in the garden, while watching her children fight. She is shown to disagree with Gideon's plan to give Luke, Jane, Katherine and Thomas part of the serum. She is shown to be crying after Gideon's death, and when her children left her. Damien Vesper comes and tries to steal Gideon's ring (for the Machina Fini Mundi) and Gideon's research (for himself), though Olivia manages to convince Damien Vesper to do otherwise (for now). Then she swore that her family will sit around the kitchen table (which all six ate at and forgot about fighting) again. She decides to name her daughter "Madeleine" and then she digs up Gideon's grave.

Part Two - Madeleine Cahill

Olivia (Babbitt) is first shown after her daughter, Madeleine attacks "an old buzzard", which turns out to be her. She sees the Vespers, and she tells Madeleine that Olivia had hoped that she would never meet the Vespers, and they were lucky they avoided them for 19 years and tells Madeleine that the Vespers dosen't know she exists. She tells Madeleine to flee and  to keep her promise, and then she runs inside the building they here hiding in (O. Babbit and Daughter Apothecary) to protect the remains of Gideon's research from Damien's hands. She then dies in a fire the Vespers lit, after she refused to open the door at Damien Vesper's men command. After her death, it was revealed that she made Madeleine promise:

  1. Keep the ring safe
  2. Never let anyone abuse the power of the 39 Clues.
  3. Unite the Cahills when time is right.

Nowhere to Run

Olivia's birthplace, Bhaile Anois, is visited by Amy and Dan. Here they find a book given to Madeleine Cahill, given by Olivia, containing the Serum Antidote. It is also revealed that Leonardo da Vinci was her teacher.



Gideon often thought that children have inherited their greatest qualities of Olivia. She saw love and beauty in things like minimal Jane. Katherine was able to fix anything. It could prove that Luke did as well as Thomas had enough strength and determination to break a door

Olivia Cahill greatly desired for her family to be reunited, and trained her daughter Madeleine to do so. She loved her family and discouraged fighting, particularly around the dinner table. She was able to trick Damien Vesper into thinking the ring was unimportant and was able to disguise herself for many years while raising Madeleine.


Gideon in the eyes of his wife was beautiful, long hair, curly and black as midnight, with piercing green eyes.


  • Intelligence and wisdom
  • Proficiency in acting


She does not appear online.


She appears on the back of Card 111: Anak Krakatau.

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