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The subject of this article appears in Cahills vsThe subject of this article appears in The Medusa Plot.

The Medusa Plot is the first book in the Cahills vs. Vespers series. It takes place two years after the Casper Wyoming Incident  in Vespers Rising. It was written by an author Gordon Korman, and was released on August 30, 2011. The logo on the cover of The Medusa Plot is red as opposed to the blue logo on the other 39 Clues books. Also, the six Cards' design and inside design are different from the other books'.


The book begins when seven Cahills are kidnapped by the Vespers all around the globe. Soon after, Dan and Amy Cahill get picked up by the school bus, which is attacked by three Vesper agents who tried to kidnap one or both of them, but failed due to the siblings' counterattack. Right after the accident, Detective Jack Corelli arrives and takes them home, advising them to get themselves bodyguards. At the mansion, William McIntyre tells them that Cahills all over the world have been kidnapped, and the Cahills then receive a text message from Vesper One on a secure phone he sent them, telling them to go to Florence, Italy by tomorrow morning or else one of the hostages will die.

Sinead Starling, McIntyre and Ian Kabra (who has arrived from London) remain in the Cahill Command Center to find more information about the Vespers and the possible whereabouts of the Cahill hostages, while Dan and Amy go to Florence, where they get a message telling them to steal Caravaggio's "Medusa" located in the Uffizi Gallery. Later, they meet up with Jonah Wizard and Hamilton Holt who help them steal the shield, but when they give the painting to the Vespers, it is found to be a fake and Vesper One sends them a video of Nellie getting shot in the shoulder.

Amy, Dan, Hamilton and Jonah then discover that the real painting was taken by a Mud Angel or Angeli del Fango named Gregor Tobin decades ago. They manage to steal the painting from him but while escaping, they lose the chargers for the Vesper phone. Ian then goes out to look for info on the phone and runs into Evan, who immediately recognizes it as a DeOssie phone and because of how Evan knows this, Ian thinks Evan has potential and then Ian then tells Evan about the Cahills and invites him to join the Command Center.

Upon further investigation of the painting, the siblings (Jonah and Hamilton have left) find Latin words (but with some missing letters) on the back of the painting, prompting Dan to ask his friend, Atticus Rosenbloom, for help. Atticus then tells Dan that the words are Porta Sanavivaria, a place in the Colosseum. Amy and Dan then travel to Rome where Atticus and his half-brother, Jake, give them a tour of the place. Dan soon finds out that the snakes in Caravaggio's "Medusa" is a map of the tunnels in the Colosseum, with the spot where two snakes bite each other as the "X". In the tunnels, they find DaVinci's "Medusa" shield, which Caravaggio based his painting on, and the original copy of a book by Marco Polo called "Il Millione" (The Million), which the Vespers were looking for. After an argument with the Rosenblooms which leads to Jake alerting the police, the siblings steal the manuscript and flee. Later, Atticus sends a message saying that Interpol is after them.

Meanwhile, Jonah, Hamilton, Ian and Sinead find the DeOssie factory in upstate New York (which they suspect to be a Vesper stronghold) and easily sneak in. After searching the whole factory, they don't find the hostages but are able to get some chargers for the DeOssie phone. On the way out, Hamilton accidentally triggers a trap by shaking a vending machine, which blows up the entire factory.

Dan and Amy finally go to give Vesper One the real painting at the drop-off, which is at a circus. At the circus, the painting is stolen by a female trapeze artist working for Vesper One right before the stadium has a blackout. As they exit the building, Dan and Amy see the acrobat dying on the sidewalk. After asking her who had wounded her on her neck, she replies, "Bruciato" (which means 'burned' in Italian, meaning Vesper One has a burn on his arm). As Amy is about to hail a taxi, they receive another text message with a photo of the hostages from Vesper One, who now tells them to go to Lucerne, Switzerland and that the hostages will only be freed after they complete a few more tasks for him.

In the last chapter, it is revealed that Vesper One was posing as a taxi driver and was driving the cab Amy had been about to hail.

Back Cover[]

One by one, distress calls start coming in from around the globe. Cahills are being kidnapped by a shadowy group known only as the Vespers. Now Amy and Dan have just days to fulfill a bizarre ransom request or their captured friends will start dying. Amy and Dan don't know what the Vespers want or how to stop them. Only one thing is clear, The Vespers are playing to win, and if they get their hands on the Clues... the world could be a hostage of them.Thirteen-year-old Dan Cahill and his older sister, Amy, thought they belonged to the world's most powerful family. They thought the hunt for the 39 Clues leading to the source of that power was over. They even thought they'd won. But Amy and Dan were wrong.

Vesper Letter[]

Greetings, Cahills!

Feel like some breaking and entering? Because I have a teeny little errand for you in Switzerland with my friend, de Virga. You better head out quickly. I still hold seven of your friends, and my trigger finger is feeling mighty itchy.

Vesper One


  • At the back of "The Medusa Plot", around the "Medusa" head, there is a URL which says Damien This will lead you to an excerpt of A King's Ransom.
  • The "Medusa" shield has a code around it. When decoded, it reads, "guardians."
  • The symbols on the first page say, "Damien is alive."
  • The symbols found on pages where the page numbers should be, when put together, say, "The mother was murdered." which probably means that Astrid Rosenbloom didn't die naturally or from diseases but rather, was murdered.
  • The symbols on the Vesper Watch card say: "Password Safe."



  • Coincidentally, this the second time the first book of one of the 39 Clues books series began with a "bad" scene. The Maze of Bones began with Grace Cahill dying while this book begins with the Cahill kidnappings.
  • This book reveals that Isabel Kabra is out of jail on parole and community service after founding AidWorksWonders, a fake charity for global disaster relief.
  • This is Gordan Korman's fourth book in the series, meaning he, Jude Watson and Peter Lerangis have written the most.
  • In mythology, Medusa was a woman with snakes for hair, and anyone who looked into her eyes turned to stone.
  • Nellie's appearance has changed over the past two years between The Clue Hunt and Cahills vs. Vespers.
  • According to Fiske later in the book, the Vesper Holding Cell may be somewhere in Mexico or the USA because he was the first to arrive (being all the kidnappings happened at the same time) because he was in California and Phoenix being the last because he was kidnapped in Tokyo. But this was thought to be inconsistent because in the fourth book, it was revealed that they were actually in Germany. However the person who told them that was lying. Later it was revealed they are at the Cascade Mountains.
  • At the end of the book, Amy and Dan become one of the Interpol's Most Wanted because their theft of the "Medusa" was confirmed.
  • In this series, Phoenix Wizard appears as Jonah Wizard's cousin and fellow Janus, even though Broderick Wizard (Jonah's father) is not a Cahill. But it could be that Broderick's brother or cousin married Phoenix's Janus mother.
  • The last page has a fingerprint on it. Due to this page being about Vesper One, this could be Vesper One's fingerprint.
  • The picture in the cover, Medusa's head is on a shield. The shield of Perseus had the face of Medusa.


The Medusa Plot - artwork