A Spy in the House had an improbable premise; a spy agency in Victorian England that is run by, and whose operatives are, women. With some suspension of disbelief, though, the story is enjoyable.
While I initially felt that Mary wasn't a Victorian heroine that was as well drawn as
Amelia Peabody or
Alexia Tarabotti, She became more intriguing and more layered as the story progressed. Through Mary issues such as race, the status of women, and socio-economic position were all highlighted without overwhelming the plot of the story. It was all subtly done, and Mary ended up being a more nuanced heroine than either the larger-than-life Amelia or Alexia.
I can only give A Spy in the House three stars, though, because I wasn't particularly interested in the foul deeds or foul people that Mary was tasked with looking into. At least Mary wasn't looking into a murder, but there was some spice lacking. I also didn't find the little quasi-romance between James and Mary to be particularly compelling or necessary.
The book was a bit of fun light reading, though, and it is part of a series that I'm interested in reading more of.