Clyde Clason's The Death Angel (1936)

The amazing story of a man twice murdered, and a killer who was successful when
the odds were 1542 to 1 against him. So reads the blurb on the title page - a
very clever blurb which is a classic misdirection in itself!

Arnold Bancroft has invited Westborough and his business partners to his house
to show off his new invention. Bancroft reveals to W that his life is in danger
and shows the latest threatening message. Even when the conversation is in
progress, W dozes off. When he wakes up, he notices that something has changed
in the room and his host is missing. Then we have the usual murder scene - an
escaped convict is on the scene, a shot is heard, there is a missing boat &
there are clear indications that there has been foul play- a blood trail which
clearly shows that whoever was shot must have gone over the cliff. With the
clues available, the house guests come to the consensus that Bancroft must have
met his end at the hands of the escaped convict.

After a series of strange occurrences in the house and some not-so-important
events (bridge, chess, juggling, magic tricks and lectures on the different
species of mushrooms), we arrive at the interesting problem. 7 people sit down
for dinner, 48 mushroom pieces are served(each guest helping himself), one
doesn't eat any, 2 out of the 6 who ate it become sick and eventually die where
as the other 4 show no ill effects. On investigating, it is found that there
were exactly 6 poisonous mushrooms out of the 48 and that there were enough
opportunities for anyone to add the 6 poisonous ones. But how could the murderer
ensure with such accuracy that only 1 or 2 could come to harm? W applies the
theory of probability to compute the eventualities and comes up with the
conclusion that the murder had only 1 chance in 1500 that exactly 2 of them
would get the 6 poisonous mushrooms!

The solution when it is revealed, obviously, appears fascinating! But it would
also need a highly credulous reader to believe that the murderer's plan would
work. This straight murder mystery (not a locked room murder) has its moments
but at the same time it has its flaws. The reason for the missing `corpus
delicti' is never explained if I remember correctly.

- Arun Pkumar (a.k.a. Poirot13)