Agatha Christie 
They Do It With Mirrors [EPUB ebook] 

A shocking crime A mansion filled with suspects Ruth Van Rydock can’t shake the feeling that something terrible is going to happen to her sister at Stonygates house.Her old school friend Jane Marple decides it’s time to pay a visit.But this grand Victorian mansion isn’t just a family home — it’s also a correctional facility for wayward young men.And when something terrible does indeed happen, Miss Marple must face her most eccentric cast of suspects yet.Never underestimate Miss Marple’If a genius is someone who leaves the field they work in totally different from how they found it, then we should certainly remember Agatha Christie as a genius.’Stephen Fry’No one on either side of the Atlantic does it better.’New York Times