Jenny Agutter & Laura Main Talk 'Call the Midwife's' Emotional Midpoint

Call the Midwife was back in tear-jerker order this week with an unexpectedly devastating new case. A young mother suffered a shocking tragedy in the final weeks of her pregnancy and needed her entire family to help her work through those trying last days. Luckily, it wasn't all bad news. Nurse Turner (Laura Main) found an incredible ally in Jill Trotwood (Joanna Horton) for promoting the clinic's measles vaccine. Jill's son, Andrew, developed a brain infection when he caught measles that left him mentally and physically disabled. She helped Nurse Turner and the nurses promote the vaccines, and Nurse Turner was able to find a way to help the Trotwood in return.

The storyline was eerily relevant as measles cases continue to increase in the United States. "We're always 54 years away from it being a period piece, but it's absolutely relevant," Main told Telly Visions in a recent interview. "Issues don't go away. Diseases, unfortunately, won't go away. It's great to be reminded and educated about all sorts of things and health issues that we have in our world. I think it's really useful."

The headline of the episode was the arrival of a new nun in training at Nonnatus House. Sister Catherine (The Spanish Princess alum Molly Vevers). The recruit arrived as Nonnatus House was determining its place within the community following the battle with the Board of Health. The new sister did not make waves in her first episode, but Jenny Agutter, who plays Sister Julienne, teased the journey ahead for Sister Catherine.