Cousin or Foe

They have been recruited to a secret agency that hasn't ever been mentioned in the world and almost died from a bomb. A criminal who tried to kill them in the future and Steven Harper. Now Otis and Allen Costo: the two teenaged spies have been kidnapped and taken to St.Petersburg, Russia to their cousin's house. But when Otis finds a document belowig to Austin labeled "R" saying to kill him and his brothers, he is suspicious and finally realize that the other side of the family have made an organization and are planning on to destroy the world. It is ime to reunite the Costo family for this big war to the DEATH. The Hastings family: the other side of the family: favourite five letter word.

Summary
Not reavealed yet.

Trivia

 * 1) This is the first book to ever have one of the Costo brother's family to be the main anatogonist.
 * 2) Origanlly, Austin Hastings was kidnapping the brothers so he could prove that he was not with The Recruitment anymore and not for a family gun.
 * 3) This book is supposed to be the most important book in the series.