Solution: Shadow of a Doubt

Written by Scott Weiss

The list of words has been encoded in a standard substitution cipher. After decoding, you get:

SOPCHOPPY (2)
RIEMANNIAN (6)
ZAPOTA (1)
GIVE OVER TO (4)
ENFRENZY (3)
PROPERER (4)
ROUSEABOUTS (3)
FLABELLIFOLIATE (4)
THEREBESIDES (7)
The blurb says "never use the same trick twice". If you use each letter in each word exactly once and anagram the set, you get:
PSYCHO (2)
MARNIE (6)
TOPAZ (1)
VERTIGO (4)
FRENZY (3)
ROPE (4)
SABOTEUR (3)
LIFEBOAT (4)
THE BIRDS (7)

All are, of course, Hitchcock films; he is the "master of horror" referred to in the blurb. The title is the name of an obscure Hitchcock film, as well.

Take the given letter from each title, and you get SETTEE BEDS. Again, reduce it to its component letters and anagram; you get the word debts.

By the way, since Hitchcock made an appearance in each of his films, I made an appearance in my puzzle. If you read the fourth letter of the first six encoded "words", you get "squonk", which is my nom de plume in the National Puzzlers' League.