On the Saturday evening before the Tom Robinson trial, Jem answered a knock at the front door: It was Sheriff Heck Tate. A group of men had gathered in Atticus's front yard. Although Jem and Scout attempted to keep up with the conversation, they could only pick up bits and pieces. They knew it was serious, however.
In Maycomb, grown men stood outside in the front yard for only two reasons: death and politics. I wondered who had died.
The children did overhear Tate tell Atticus that they would be
"... movin' him to the county jail tomorrow... I don't look for any trouble, but I can't guarantee there won't be any..."
The men, led by Sheriff Tate, had gathered to warn Atticus that Tom was being moved to the county jail, and that there could be trouble. They were mostly worried about the men from Old Sarum, but Atticus thought things would be okay since the Old Sarum bunch "don't usually drink on Sunday." As Atticus found out the next evening, there certainly was a reason to fear the men from Old Sarum and their desire to put an end to Tom in their own manner.