The fifth of seven brand new 39 Clues stories, leading up to one explosive reveal.

Amy Cahill knows her family needs to be prepared for the next Vesper attack, so she organizes a training weekend at the brand new Cahill command center. However, Dan and the others would rather goof off than hone their secret agent skills. Can Amy channel her inner leader and bring everyone in line? Or will a surprise appearance by a Vesper assassin prove that she's in over her head?