Mayella Violet Ewell is called to testify in the trial of Tom Robinson in Chapter Eighteen of To Kill a Mockingbird. Mayella takes the stand and asserts that she was sitting on the front porch of her family's home when Tom Robinson passed by. Mayella claims that she had asked Tom to "bust up" the old chiffarobe for her in exchange for a nickel; when Mayella went into the house to retrieve the nickel, she states that Tom followed her, grabbed her by the neck, and began hitting her and cussing her--a violent attack which allegedly ends in Tom raping her.
In his cross-examination of the witness, Atticus demonstrates that Mayella is motherless, uneducated, friendless, and unfairly made responsible for the well-being of the family, including her drunkard father. These circumstances have fashioned her into a very lonely woman who attempted to seduce Tom and to lie about it when this attempt was witnessed by her father.
Although Mayella's unreliable testimony and Atticus' cross-examination both suggest that Tom is innocent, the man is unfairly found guilty at the hands of the failed and prejudiced judicial system.