Trouble arrives at the Dashwood household in equine form when Marianne announces that Willoughby has given her an extravagant gift: a horse. Yes, that's right, you read right – flowers and chocolates just won't suffice for this guy. Horse it is.
Elinor can't believe that Marianne has accepted such a ridiculous gift – after all, the Dashwoods can't afford all the things required to house a new horse (like, for instance, a stable). Marianne dismisses her sister's complaints about both the horse and Willoughby.
However, Elinor manages to convince Marianne to turn down the horse, after reminder her of how much trouble it will be to their mother.
The next day, Marianne regretfully informs Willoughby that the horse is impossible. He assures her that the horse will be waiting for her, until the Dashwoods are able to take care of it.
Elinor overhears this exchange, and becomes convinced from Willoughby's concern and intimacy with Marianne that the two are engaged.
Margaret, the youngest sister, is also convinced of the same thing. She tells Elinor excitedly that Willoughby even has a lock of Marianne's hair (a really big deal in those days).
Margaret, apparently, is kind of a ditz – she almost reveals the secret identity of Elinor's favorite gentleman (Edward) to the curious Mrs. Jennings one day. Basically, she's a normal, gossip-loving preteen.
Margaret reveals to everyone that Elinor's mystery man's name starts with an "F." Fortunately, everyone is distracted by a combination of things, and Elinor is left mercifully alone (for the moment).
The party plans to go on an adventure to visit a beautiful estate nearby, owned by Colonel Brandon's brother-in-law, despite the bad weather.