6 year old Hetty Feather and her little brother, Gideon are forced to leave their "borrowed" family and return to the Foundling Hospital which the fearsome Matron rules with an iron fist. When Hetty meets up with Mathias and the gang from the boys' wing they hatch a high risk plan to escape the hospital for good. Can they scale the walls in search of freedom or will the She-Mob and Matron catch and punish them?

With Hetty framed by Sheila and locked up by Matron it looks like Hetty won't get the escape letter to Matthias in time for their midnight breakout. But maybe she can break into the boys wing and finally meet Gideon and put the escape plans in motion.

It's Gideon's borrowed-birthday but how can Hetty celebrate with her brother when girls are not even allowed to mix with the boys? With a plan to scale through the rafters and into the towers can the two wings secretly come together without Matron finding out, and not to mention the dangers of getting across the roof at night?

Mathias is back and a shadow of his former fearless self. With the Hospital on lock down in order to mass produce toys supposedly earmarked for charity, children start falling ill and Gideon tries to enlist Mathias' help to get to the bottom of Matron's toy making venture.

Hetty's feisty little borrowed-sister, Eliza, arrives at the hospital and like Hetty clashes with Matron. When Matron's sister, Annie arrives to deliver bad news about their dying mother, she also tries helping Eliza and Hetty in their battles with Matron. But can Annie help her own sister make amends with their frail mother before it's too late?

Kindly Nurse Wintson is sacked by Matron. So Hetty convinces the children to go on strike. Will Matron capitulate before the choir debut their new anthem in order to win a £100 donation for the school's organ? Or will Hetty lose support and be crushed by Matron?