This was a 3.5 star read for me.
It's 2089 and Helen Foster is a genetically enhanced American soldier, fighting the Nazis. Due to the discovery of a superweapon, World War II never ended, and has rumbled on over the intervening hundred and some years. But now the higher ups have discovered that it might be possible to send someone very special back in time to obtain the plans for the superweapon and thwart the Nazis' plans. Helen is that special someone. The trouble is, it's a one way trip, and she can't take anything with her, not even clothing. Thanks to historic documents, she does know when and where the plans will be sold, and she can obtain money by blackmailing an illegitimate Duke. So she's packed off through time to 1853, with orders to save the world then fade quietly into obscurity so that she doesn't change the timeline any further.
Unfortunately, Helen has had minimal time to prepare, and she finds her sweary soldierly self adrift in a society which she quite clearly doesn't belong to. Grappling with social niceties and corsets are only part of her problem though, as, of course, the Duke is not at all happy about brash Helen and her blackmail. When her mission to buy the weapon plans are thwarted, she is forced to turn to him for help. But Edward is not prepared to let her have her own way, and inserts himself into her life to ensure he gets his hands on the diary she is using to blackmail him. He's drawn to this strange woman and the escape from his regulated, dull life, and so it becomes a matter of whether they can trust one another.
This was a very short book, and a quick read. I'm not entirely sure why Helen was given so little time in the future for prep—after all, she's going back into the past, which isn't going anywhere or changing until she gets there. There's a lot of swearing and some moderately explicit sexual moments, so if you prefer your historical romances clean, this probably wouldn't be the book for you. There's not a huge amount of world building in either the future or the past, and a few historical errors have crept in. If you're a stickler for accuracy these might annoy you. I tend to work on the principle that I've already suspended my disbelief sufficiently for the time travel side of things, so I can perfectly well hoist it a bit higher and deal with the presence of pound coins and Canary Wharf being on an ocean rather than a river.
This was a fun romp, but it felt like half a book, especially as it ended rather abruptly. Looking at the sequel, which seems to be even shorter, I wonder if this might have been better if the two separate short books were just put together as one longer novel. Helen and Edward are entertaining central characters, a definite case of worlds colliding. The villain was a bit limp, ultimately, and Nazis as the Big Bad has perhaps been a mite overused in alternate history fiction. I'll probably pick up the sequel at some point.