Tom Robinson was accused of raping Mayella Ewell. Everyday Mayella had a chore or job for Tom to do, as Tom walked home everyday. Tom said he did these for her because he "felt sorry for her," but when he said that in court, it was unacceptable because at the time, a black man could never feel bad for a white person. 

She invited him into do a chore one day and took him to her room and kissed him, but she didn't realize her father was watching. Bob Ewell saw what was going on, and he came in and started beating Mayella. Tom ran not because he was guilty, but because he knew that no one would believe that he didn't initiate what had happened. Mayella's father decided to take it to court, probably to cover up what he was actually doing to her at home, and Mayella stayed on her fathers side, out of fear of her father and out of shame for liking a black man.

In the courtroom, Atticus proves Tom is inocent because Mayella has a bruise on her right eye and and tom couldn't use his left hand because when he was younger his left arm had gotten caught in a cotton gin and ripped it apart. Atticus had Bob sign his name on a piece of paper, and saw that he signed it with his left hand, proving that it could've been Bob Ewell that caused the bruises on Mayella, and not Tom. Atticus proved Tom innocent, but because of racial discrimination in this time, he was guilty, all because he was black. The jury should've come into the courtroom in the first place with no racial bias to have given Tom a chance at all.