This is basically a country-house murder mystery except that the setting is not a country house but a mid-1960s WorldCon. To be honest the identity of the murderer is fairly obvious from the first chapter, once you work out who of the characters described in detail is the Detective, the Sidekick and the Villain. But it's a fun and fairly brief read.
Also I look forward to someone publishing a key to the identities of the real-life characters identified here by pseudonyms. Big-Hearted Howard isn't even a pseudonym, really, and I am guessing that Gary Corneille is Jerry Pournelle, but I don't immediately identify any of the rest; also the murderer's surname is very nearly an anagram of a well-known (but now deceased) famous SF author.
V'z abg ernqvat gbb zhpu vagb gung, nz V? "Dhragva Ebqrffn" ybbxf gb zr yvxr n ersrerapr gb "Cbhy Naqrefba", nygubhtu gur fheanzrf ner sne sebz orvat cresrpg nantenzf.