Answer: The mood is uneasy, perhaps ominous; there is a sense of foreboding.
Explanation: inclusion of details such as the "stealthy steps" outside his room, the "dark and silent" chateau, "black noiseless forms" moving in the pattern of shadow, and the "sallow moon" create a mysterious scene which the protagonist, Rainsford, is sleepless, disturbed by the sounds and sights in his surroundings.
