Korman, Gordon <br/><br/>
Medusa Plot, The :  Cahills vs. Vespers. 

 - New York, NY :  Scholastic,  2011. 
 - 222 
 - 39 Clues .
<br/><br/> 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 39 Clues leading to the source of that power was over.  They even thought they'd won.  But Amy and Dan were wrong. 
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<br/><br/><label>ISBN: </label>9780545324090