This was a quick read. I liked all three characters, especially protective Eleanor. Sometimes I was annoyed with Marie for making dumb choices, though.
The first part of Marie's story centered on her training. I found that interesting and was looking forward to seeing her apply that training in the field. However, after Marie was deployed, there was very little written about her being a radio operator. Mostly what we saw was the odd jobs she was called upon to do that stretched her beyond her training. I imagine the author chose to focus on those actions for the sake of flow and tension, as this was where the suspense really started, so I can understand that.
There was a development that really bothered me, though. At one point Marie sent a message to London, and the response she got was something I couldn't imagine even the greenest rookie sending. Yes, it is fiction, and the response moved the action along the way the author needed it to, but unfortunately it felt unbelievable to me.
Overall, however, I found this an interesting read.