I picked up The Moonlight Mistress by Janssen thinking it was erotica with paranormal elements and a bit of a historical background, especially after reading the above book description. Instead I found much more. The story begins in Germany right as they invade Belgium and WW-I explodes and introduces the reader to Lucilla and Pascal -- the core couple. However, most of the story takes place in France after the Germans invade that country and as war rages on.
There are multiple protagonists in The Moonlight Mistress and some of them are part of an English battalion fighting in France. The war is not used as background, instead Janssen thoroughly develops the plot and cast of characters while incorporating well-written historical details and making the war part of the story. The reader is right there with those men as they dig ditches, sleep in the mud, and as they experience battles, hunger, losses and small victories. Janssen cleverly integrates the historical details into the paranormal aspect of the book; an unexpected and pleasant surprise.
The erotic scenes are great and don't overwhelm the story, although there are plenty. The couples are all likable and their relationships are thoroughly developed. There are M/F, M/M and M/M/F erotic scenes to go with the storylines Ms. Janssen weaves into The Moonlight Mistress. The M/F scenes start on the warm side with Lucilla and Pascal and get hotter as the story goes on. In the beginning sexual tension is used to develop the M/M relationship, however the sexual encounters are hot from beginning to end as is the M/M/F. You will find that all the female protagonists in the story are either strong women or women with a defined path.
The Moonlight Mistress is a well-written, enjoyable adventure with well-developed characters, hot, erotic encounters, and thorough historical details cleverly incorporated into the overall story.