Ahh, this was lovely. The bones of this are Agatha Christie, its a locked room mystery on an interstellar cruise liner. The twist is that it is structured like Hammet's the Thin Man and uses that as the character templates for the protagonists.
It sailed along with brim and vigor and no small amount of wit. A vastly entertaining romp with some science fictional elements. Given this is Kowal, the space and speculative tech elements are spot on as well.
It wasn't 5 stars for me because I felt some plot elements didn't come together at the end but that's probably more a me thing. I inhaled this in like 2 sittings while away for the weekend and I thoroughly enjoyed it.
Definite recommend.