Ngaio Marsh 
Grave Mistake 

Another classic Ngaio Marsh novel.At first it looked as if Sybil Foster had intentionally left the world: with two husbands dead, a daughter marrying the wrong man and – it later appeared – a debilitating disease, it was no wonder she took her own life.But no one believed she was the type – especially Chief Superintendent Roderick Alleyn. For the field was ripe with unfortunate engagements – one of them a very grave mistake…