Still looking for a way to find the elusive Sam, Neal pins his hopes on an email address being monitored by an unknown party in Washington D.C. But while Neal and Peter have agreed to work together when it comes to Sam, they both secretly realize that the reality of the situation isn't nearly that simple.
Meanwhile, Mozzie stumbles into the middle of a mystery dating back to the American Revolution when he is mistaken for the descendant of a member of the Culper Ring, a network of secret operatives created by George Washington. While Peter finds talk of Revolution-era spies and secret codes tough to swallow, Mozzie's head is spinning, especially after he comes in contact with a real life Culper descendant in possession of old letters that point the way to a priceless antique flag. But a disgraced professor is also hunting for the flag and he'll go to any lengths to obtain it.
With one person already dead, Peter and Neal will have to embrace the unbelievable case wholeheartedly. Little do they realize just how much Mozzie has invested in living out this spy fantasy to the fullest...