Unfortunately, Dr. Clarkson was right. Something is wrong with Sybil.
The new mother starts seizing in the middle of the night. The room becomes chaotic. Cora is crying, Robert is yelling again. Sir Philip doesn't really know what is going on or what to say. Mary starts shaking her sister. Edith just stands there like a deer in the headlights. Matthew is astounded that something like this could happen in 1920. At least they all still look elegant in their pajamas.
Robert becomes indignant with Sir Philip. "You were so sure!" "The human life is unpredictable," Sir Philip says. That's what you get, Robert. For not listening to your wife, or your daughter's doctor.
As Tom begs her not to die, Sybil goes limp. And suddenly, we're all devastated. Rest in peace, dearest Sybil. (Rumor has it that Jessica Brown Findlay wanted to pursue a career outside of Downton. But did Sybil really have to die? It would have been easy to keep her around, right? Just figure out a way to send Tom and Sybil back to Ireland and then there's always the possibility that she could come back. Oh well.)
The downstairs contingent hears of the news. Thomas is particularly affected -- he tells Anna that Sybil is one of the few people who was ever nice to him. I guess they really bonded over that blind guy who killed himself back in season 2. (I shouldn't be so harsh; I actually felt bad for Thomas here. He so rarely shows his human side.)
Cora wants a moment alone with Sybil's body and she asks Mary to tell Lord Grantham to sleep in the dressing room. (Uh oh.) Cora promises her lifeless daughter that she will take care of Tom and the baby.
After they take Sybil away, Cora says she's going to write to Dr. Clarkson to apologize. "Because if we'd listened to him, Sybil might still be alive. But Sir Philip and your father knew better and now she's dead." Robert is definitely not off the hook.
(If Julian Fellowes wasn't British, I'd say that this was one giant metaphor about the dangers of American politicians trying to legislate women's health issues. Or am I stretching it just a bit?)
NEXT: Yes, other things happened, too