When the body of four-year-old John Vincent is discovered, hidden in a midden, the already unhappy

Cornwall family begins to unravel. With no obvious reason for his murder, a scapegoat must be found and

his elder half-sister Charlotte, the sleepwalker, neatly fits the bill.

After facing the horror of a trial by jury, Charlotte is found not guilty but suspicion still follows her as

she takes up almost unpaid work as a teacher in the untrustworthy Mrs. Armitage's school.

After her fellow teacher and friend, Miss Lamb, vanishes, followed by the tragic death of one of

Charlotte's much-loved pupils, the finger of blame is pointed again. Now even Charlotte begins to

believe that she is losing her mind and may well be a murderess.