Natural Causes is black comedy at its blackest and best.
Walter Bryce contacts Vincent, a travelling salesman who trades in a potion designed to help people commit suicide and move painlessly into the next world. He arrives at Walter's country house and mistakenly assumes that the potion is for Walter's consumption.
It becomes clear that the client is Celia, Walter's wife − or is she?
Why are all her suicide letters typed and unsigned?
After several thwarted attempts to poison various characters (resulting in the multiple poisonings of a rubber plant), will anyone manage to drink the potion?