Our story beings with Walter Hartright helpfully telling us that he's about to tell us a story. (Glad he gave us that head's up.) Walter actually gathered a lot of testimony and letters from people to tell us a dramatic and totally true story. Cue the Law and Order theme song.
So Walter is an art teacher who lands a gig teaching two sisters how to draw. Before heading out to the sisters' house, he meets a mysterious woman dressed entirely in white who has just escaped from a lunatic asylum.
Walter heads to Limmeridge House, where he promptly becomes BFFs with the older sister, Marian, and falls in love with the younger sister, Laura. Marian and Walter investigate the woman in white, who is named Anne Catherick and who bears a weird resemblance to Laura.
But then Walter has to leave because of his love for Laura, who is already engaged to a dude named Sir Percival Glyde. Walter peaces out and Sir Percival arrives on the scene and woos his Laura some more for good measure. But Anne Catherick sends a letter to Laura prior to her fiancé's arrival. The letter tells Laura to stay away from Sir Percival—he's a creep. Sir Percival also makes some shifty legal demands regarding Laura's inheritance, which the family lawyer doesn't like. Laura hems and haws about everything but finally decides to marry Sir Percival anyway, since she promised her dad she would. Marian is less than pleased with the situation.