Trick — Gerard Houarner

When living by yourself, it's easy to let little things spook you. Sometimes
your mind even plays tricks on you. Roger Cassidy lives alone. He thought he
got a great deal on his apartment, but then the knocking began. Knocking on
his door that comes and goes, but with no one there. Roger is determined to
figure out the mystery of why this is happening, and on Halloween night
he'll get more answers than he ever dreamed...