Galaxy X is the third Hardy Boys Undercover Brothers trilogy. The first book, Galaxy X was published in May 2009, with books two, X-plosion, and three, The X-Factor following in July and September, respectively.
Galaxy X is the third Hardy Boys Undercover Brothers trilogy. The first book, Galaxy X was published in May 2009, with books two, X-plosion, and three, The X-Factor following in July and September, respectively.