A street girl breaks into the hospital looking for safety and Hetty must help by disguising her as a foundling. However, they are unaware that Matron has her own reasons to find the young girl before anyone else.

Will Hetty find the secret book that could bring Matron's downfall? And why are so many of the foundlings falling ill?

Hetty discovers that others are planning a daring visit. Meanwhile, Vince blackmails Nurse Winterson to get special treatment.