A militia unit arrives at Meryton for the winter. Meryton is a town about a mile from Longbourn, where the Bennets live.
The two youngest Bennet girls, Catherine and Lydia, are super excited about all the men in uniforms.
Let's put it this way: If the military were a rock band, Catherine and Lydia would be the groupies plotting ways to sneak into the band's trailer.
Jane is invited to Netherfield to have lunch with Mr. Bingley's sisters, Miss Bingley and Mrs. Hurst, and Mrs. Bennet figures out a way to game that situation: Jane can go on horseback instead of in the carriage, so she'll have to stay overnight if it rains.
It works—a little too well. Jane gets so sick from her drenching that the Bingleys urge her to stay until she recovers.
Naturally, Lizzy walks three miles in the rain to Netherfield to check on Jane.
Everybody at Netherfield is surprised to see her, but Mr. Darcy sure thinks she looks pretty with her cheeks all flushed from the walk.
Jane is glad to see her, and Elizabeth even begins to like Mr. Bingley's sisters when she sees how affectionate they are towards Jane. They even ask Lizzy to stay overnight.