I enjoyed the story and the characters in this gender-bender tale of intrigue. However, there are a few glaring details that you need to be able to overlook in order to enjoy the story.
One, that our hero, the main character who is supposed to be a seasoned spy, doesn't notice that Flip is a a woman but Robbie his 9 year old ward and everyone else wasn't fooled. It's really hard to swallow especially since he's also the spymaster of the Liar's Club. It just seemed like he's too dumb and unhinged due to a previous perceived betrayal.
And as a spymaster, he was also too reckless in hiring Flip and not keeping his other life separate. All these little things just made it hard to believe that he's capable of being the spymaster in charge.
However, if you can overlook these things, the story is pretty engrossing. The characters do a depth to the story but the storyline drives itself.