The group I run for has a GM of the year contest and as part of that we get critique cards from our players.  Generally my reviews were good but I got one this year has me scratching my head and feeling a bit out of sorts on how to fix the issue.

I ran an RPG this year based on the 1968 film- Where Eagles Dare-  one of my all time favorite films. The basic premise is that a group of US and British spies must break into impregnable Nutzi (Gen Con screens the real word)fortress rescue a prisoner and escape.  There are 4 male and 2 Female NPC's as per the movie. The male spies come in pretending Germ Soldiers the females come in separately undercover as a bar maid and domestic help for the castle 

My game was three players short of the full ... and one of our other games had only one player show up (both were supposedly sold out, but that's another thread).  I asked the 20 something female player at the other game if she would like a refund or join our game.  She chose to join ours.  She choose the PC that goes under cover as a maid.  This PC has the strongest firearms skill in the game... in the Film she rescues Clint Eastwood and Richard Burton on at least 3 occasions... in game she gets some of the most NPC interaction and she is in a position to end  part of the mission from the first 15 minutes of the game.  I find her to be a very strong PC.  At least that's how I thought I wrote her.

SO on the comment card the player that she felt it demeaning to play a maid - I spelled out in mission briefing and on her character sheet she was a spy and assassin...   She felt isolated from the other characters because she was dropped in separately-  As in the movie... and felt she was belittled as a female character....

How do I handle this differently the future?  I'm not really sure what to do here.

My first question would be: 
What did that character get to do in the game?

I've run into trouble in my own games where a character who was awesome in the source material just didn't work as well in the game, often because the interaction between characters wasn't the same.

Was there much time between the start of the game & all of the characters being able to interact? 
I'm 100% guessing here, but if there were early scenes where the rest of the party got to do things and build more of a player/character rapport, it could feel like you were excluded?

That's one of my favorite movies too!

I think that's actually a good critique.

I'd suggest being more upfront during character selection. If someone is interested in playing Mary, I'd take them to the side and explain their real mission, their only connection to Smith, their mutual suspicions about the other characters, and how the game will work until all the characters are together in the same area (splitting the party is particularly problematic in short con games just due to the fact that half the time some people don't have the chance to participate while you are focusing on the other characters).

Female undercover as a maid, while logical, does seem less exciting. You could update Mary to a cover of a "translator" who is brought in to help interrogate the American General.

I think having a separate character from the rest of the party for a lot of the game is just not as effective in a RPG compared to the movie. Maybe you could have Mary as a "side" character, that you play as an NPC, and then if a character gets kills, the player could take her over as the assault in the castle takes place. Or you could beef up the spy side, and have more characters sneaking in as civilians, while the commando squad does it their way at the same time.