<P> On April 26, 2014, at the New Hampshire Worlds Collide event, Scholastic announced a fourth series titled Doublecross . The series began with Jude Watson's Mission Titanic (2015), followed by C. Alexander London's Mission Hindenburg (2015) and Jenny Goebel's Mission Hurricane (2016). The series concludes with Sarwat Chadda's Mission Atomic published on June 28, 2016 . Amy, Dan, and their allies try to thwart the Outcast's plans of mass destruction . </P> <Table> Mission Titanic <Tr> <Th> Author </Th> <Td> Jude Watson </Td> </Tr> <Tr> <Th> Series </Th> <Td> Doublecross </Td> </Tr> <Tr> <Th> Published </Th> <Td> February 24, 2015 (2015 - 02 - 24) </Td> </Tr> <Tr> <Th> Preceded by </Th> <Td> Flashpoint </Td> </Tr> <Tr> <Th> Followed by </Th> <Td> Mission Hindenburg </Td> </Tr> </Table> <Tr> <Th> Author </Th> <Td> Jude Watson </Td> </Tr> <Tr> <Th> Series </Th> <Td> Doublecross </Td> </Tr>

What is the treasure in the 39 clues