Esther is teaching Charley how to write. It's not going too well, even though Charley has great hand-eye coordination. (Quick brain snack: modern science has confirmed that it is much harder for adults to learn to read and write than for kids. Their brains are no longer as plastic and adaptable.)
Charley tells Esther she has seen Jenny, the brickmaker's wife, getting medicine for a poor boy.
Esther decides to go investigate.
When she and Charley get to the cottage where Jenny and her friend Liz are staying, they see Jo, who is clearly suffering from some kind of severe fever.
He loses it when he sees Esther, getting her confused with the veiled lady and the French maid and yelling that he doesn't want to go back to the cemetery.
No one knows what he's talking about, of course, and they figure he is delirious.
Suddenly Jenny realizes that her husband is on his way home, drunk as usual, and everyone has to clear out before he gets there. It's clear that he beats her all the time, and she doesn't want to set him off.
Meanwhile, Jo is getting worse. This is before antibiotics, and any old infection could just kill you. People were dying from pink-eye all the time.
Esther and Charley make him follow them home to Bleak House, even though Jo is kind of terrified of Esther.
At home Skimpole flips out (as much as he can) and tells them that Jo clearly has a terrible fever and they need to get him the heck out of there – even if that means he's going to die.
Jarndyce is all, um, no.
They take as much care of Jo as possible and put him in the barn overnight.
(This is just before the germ theory of disease is understood. Victorians know that feverish people are contagious but not exactly what makes the disease spread. Touch? Air? Some kind of blood pollution? Dirt? There were many theories.)
So anyway, the next morning, Jo is gone. No, not dead, actually gone – he vamoosed in the middle of the night.
They spend five days trying to find him, but no luck.
But... Charley catches whatever he had and becomes extremely ill.
Esther takes care of her exclusively. She forbids Ada to come anywhere near them, closes off their part of the house, and takes extreme disinfecting precautions.
Charley gets worse, and worse, and worse. She is delirious, talks about her family, raves a little, and then... gets better! Yay!
Except, no. Because now Esther is sick too.
Charley, since she just got over whatever the illness is, was immune, so she can take care of Esther. Esther doesn't tell the rest of the house that she is ill yet.
The next day she wakes up... blind. Wait, what? Oh, man!