Irina Spasky

This is the list of fictional and non-fictional characters who appeared in The 39 Clues franchise. They may appear in The 39 Clues books and audiobooks, cards, or the series' official website.

Ian, Natalie, and Isabel Kabra (all from London, United Kingdom) are the richest and most ruthless team in the quest. Isabel Kabra née Vesper-Hollingsworth is the wife of Vikram Kabra, both of whom are the billionaire parents of Ian and Natalie. Ian is fourteen years old while Natalie is eleven. Both children have cinnamon-complexion skin. Ian is interested in jets while Natalie is a shopaholic. Ian also has feelings for Amy Cahill, despite the disagreement of his mother. Natalie always carries a poison dart gun with her for protection. Isabel, on the other hand, is an art dealer like her husband Vikram. She is so desperate for Clues that she is even willing to risk the lives of others, including her own children. She also killed four people; including Hope Cahill, possibly Arthur Trent, Irina Spasky, and Lester Dixon. Originally, siblings Ian and Natalie are the only ones who accepted the challenge. In the sixth book, Isabel officially joins her children due to her annoyance to them always failing to find Clues. In the end, Isabel was imprisoned for the rest of her life, and as a result of their parent's fates, Ian and Natalie are now the current leaders of the Lucians. Isabel was sentenced to life in jail with no chance of parole by Vespers due to her failing her mission. Isabel found a way back into the world her cover is AidWorksWonders. In Day of Doom, Natalie is electrocuted on the Machina Fini Mundi. Isabel sees Natalie's dead body and drinks the Master Serum, attacking Vesper One. The device then explodes, killing Isabel and Vesper One. They are all Lucians. The Kabras are deadly. Their respective cards range from No. 178 (Ian), No. 112 (Natalie), and No. 177 (Isabel).

The Holt family is composed of Eisenhower, Mary-Todd, Hamilton, Madison, Reagan, and Arnold Holt (all from Milwaukee, Wisconsin, except Mary-Todd, who is from Daytona Beach, Florida). They are the strongest team in the quest. Eisenhower and Mary-Todd provide as the parents of Hamilton Pierre, Madison, and Reagan. Arnold, the family pit bull, is also considered as member of the family. Hamilton is fourteen years old while identical twins Madison and Reagan are both eleven. The whole family commonly wear matching purple jogsuits, and they always travel with Arnold. Eisenhower is a failed soldier and agent from the United States Military Academy and Federal Bureau of Investigation, respectively; and has been working as a security guard since then. He was apparently expelled from West Point Military Academy due to an accusation by Arthur Trent, who was his roommate. He is also one of those witnesses of Hope Cahill's and Arthur Trent's deaths. Hamilton is a member of his school's football team, and is a master of parkour. He is also good in technology and computers as well. Throughout the books, Hamilton provides the best defense for Amy and Dan Cahill during their alliances, especially in Into the Gauntlet. Madison is good in ice hockey while Reagan's profession is kickboxing. Reagan, however, is the most compassionate member of the family, and she is as well taking ballet lessons. Hamilton, Madison, and Reagan are considered as their school's bullies. Arnold is very fond of biting others. They are all Tomas. Their respective cards range from No. 145 (Eisenhower), No. 238 (Mary-Todd), No. 90 (Hamilton), No. 187 (Madison), and No. 123 (Reagan). Arnold's official cards are No. 403, No. 412, No. 414, and No. 418.

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