In the story, the tradition of the town is to pick one person from the lottery to be sacrificed for some certain reason. In the text it states, "The people of the village began to gather in the square, between the post office and the bank, around ten o'clock;". This shows that the people take the tradition very seriously.
In the story, Tammie is running late to the lottery, this made her stand out from the begging inferring something was going to happen to her. In the text it states, ""Here comes your, Missus, Hutchinson," and "Bill, she made it after all." Mrs. Hutchinson reached her husband, and Mr. Summers, who had been waiting, said cheerfully." This infers something bad might happen to her.
In the story it's really suspenseful towards the end due to Tammie panicking about how the results of the lottery. In the text it states, "Tessie Hutchinson was in the center of a cleared space by now, and she held her hands out desperately as the villagers moved in on her. "It isn't fair,". This shows that the mood is visibly panicked.