After her soldier husband is seriously injured and her marriage begins to fall apart, Meredith Cordingley returns to teach at Letchford, the grand Cotswold private school run by her father. The setting provides Meredith with a refuge until one September afternoon, when a shocking discovery is made in the history room. The police are called, but all is not what it seems. Meredith is determined to discover the culprit and becomes convinced that a manipulative member of staff is exerting a calculating influence on a vulnerable student. On her journey to untangle the truth Meredith comes to discover that there is more than one person at Letchford School hiding a past filled with complicated secrets.