Here’s the spoiler-free version: the action, which is spectacular in both senses of the word, is just the tip of the iceberg. Unfortunately, it’s hard to explain what’s so clever about the series without getting into at least mild spoilers. While the three books are quite different (in tone and even in genre 1) from one another, they nonetheless form a clever, often dark, and surprisingly restrained story – and it is a single story each book is one part of the greater whole, not a standalone. In the hands of 99% of authors, the result would have been pulpy, campy, trashy. The trilogy takes place in a world where Nazi Germany fields superpowered warriors and a desperate Britain responds with forbidden magic. Together, they form proof that a good author can outshine the most hackneyed premise.
The Milkweed Triptych, by Ian Tregillis, comprises three novels: Bitter Seeds, The Coldest War, and Necessary Evils. Sadly, the US publisher switched cover artists after the first book. One of the best speculative fiction covers I’ve seen in a while.