Patsy and Delia had never seen such a thing. The older nuns had seen it before, a decade ago, and even earlier. Even Phyllis had seen it. They called it a “pea-souper,” a thick fog. The last “pea-souper,” the Great Smog of London, was hard to see through and dangerous to breathe in. This fog was not as thick as the Great Smog, but those that lived through it thought this fog was just as dangerous.

Patsy and Delia knew, as they looked at each other in Nonnatus House, they were not moving into their flat just yet.