Harper Lee's use of Gothic elements in "To Kill A Mockingbird," such as the fire and the mad dog, escalates the suspense that faintly foreshadows Tom Robinson’s trial, its outcome and his subsequent tragic death. Other events that are foreshadowed in the novel include the kindness and gentle nature of Boo Radley, the maliciousness and meanness of Bob Ewell and Bob Ewell's attack on Jem and Scout Finch.
On Scout's first day of school, her classmate, Burris Ewell, speaks to the teacher in a cruel and vulgar manner providing the reader a glimpse of what his life is like at home. This foreshadows the vindictive and evil disposition of his father.
Jem's pants left mended and hung neatly over the fence, the presents left for Jem and Scout in the oak tree and the blanket placed lovingly on a freezing Scout the night of the fire all combine to subtly suggest that Boo Radley is much like a "guardian angel" to the Finch children and will be there if and when they need him, according to SparkNotes and Synonym.
In the weeks leading up to the night Bob Ewell attacks Jem and Scout, he hints at his intent when he tells Atticus, after Tom Robinson is killed in prison, "One down, two to go." His blaming Atticus for his firing from Works Progress Administration, as well as his threats to Atticus, fills the reader with a sense of foreboding.