The story deals with the two friends Harry Norman and Alaric Tudor, who work at the Weights and Measures Office, and with Alaric's cousin Charley, who works in Internal Navigation. Harry falls in love with Gertrude Woodward, the eldest of the three beautiful daughters of a clergyman's widow, while Alaric pursues Linda, the second daughter. Gertrude rejects Harry's marriage proposal, and Alaric, rising in the ranks of the civil service, pursues and gains Gertrude's hand. Harry is unable to forgive Alaric, but eventually he marries the second daughter, Linda, and later becomes a country squire. Alaric meanwhile, becomes a Commissioner, but he falls under the influence of an unscrupulous member of Parliament, Undy Scott, who talks him into various schemes of dubious legality and morality, which eventually lead to his downfall. Charley Tudor is considered a rake, who spends his time at London's public houses and gin palaces. However, he dreams of a cleaner life, and loves Katie, the youngest sister, who falls in love with Charley after he rescues her from drowning in the Thames. Charley is also engaged to an Irish barmaid, and Katie's mother considers Charley an unsuitable husband, and forces him to swear never to speak to her.

Question: Who does Charlie rescue in the Thames?
Answer: Katie
Alternative answer: Katie