Liu makes extremely good use of the novella length for his story, which is a gripping, at times painfully so, story. It shines a light into a dark place during the Second World War, a camp whose biological and other medical experiments on those interred there were a match for horrors in much better known places.

It takes the form of documentary transcripts, but as the verbatim transcripts gradually unfold the true horrors, and the politics that have kept what happened mostly unknown, the voices of the victims and the observers are powerfully resonant. The story uses time travel to bring to light what happened, and it’s several steps beyond most SF in impact.