Imagine an institution where 125,000 children are admitted - and 100,000 die or go missing. This is the story of the Dublin Foundling Hospital. Its mission: to take in the children of poor Catholics and raise them as loyal Protestants. Lying at the very edge of the eighteenth-century city, behind high walls and forbidding gates, the Dublin Foundling Hospital was often the object of horror and curiosity during its lifetime. But following its closure this enigmatic institution seemed to slip from the city's memory. Based on new research, this book tells the dramatic story of the Hospital, including the tattooing of every child admitted with an identification number and the feeding of opium to thousands of children, hastening their deaths. Above all, the author searches for clues as to what happened to the children and why the institution was protected and allowed to continue for a hundred years.