There need to be more cross-over stories between authors I enjoy because the end-products are often enjoyable and entertaining. This long-ish short story (short novella?) is both a great mystery that the two sets of partners would naturally have become involved in and complete fan service. I have nothing to complain about either elements.
My only quibble is that this might have worked better from Robert and Griffin’s points of view instead of Robert and Whyborne, but these narratives had already been established by the authors, so I understand the reasoning.
Rating: 4 (out of 5) stars. Cross-posted to Goodreads.