Journal of the Supernova

The nearby star Betelgeuse is about to explode, an event whose consequences for life on Earth are uncertain. Hugo Evans, an American art historian living in London, receives an invitation from a man he has never met, reclusive artist Rothesay Ambrose Urquhart, to an "end-of-the-world" Mediterranean cruise aboard the meticulously restored prewar motor yacht Mulvane. There are twelve guests in total, all strangers to one another, and also to their host. 

Early in the voyage, one of them is lost overboard. It is not clear if this was an accident, a suicide, or a murder. Another passenger, sharp-witted lawyer Oriana Welles, recruits Evans to help her investigate.