《不可遗忘》第三季于2018年7月在英国播出,这部剧每一季都涉及一个新的案件,介绍似乎没有关联的人物,这些人逐渐被揭露与受害者有某种关系。随着谋杀之谜的揭开,犯罪的情感影响也在那些受影响的人的生活中被探索。When the twenty year old remains of a young woman are unearthed by workmen Cassie and Sunny become involved. All they can deduce is that she broke her arm whilst on vacation in Cyprus but this leads to identifying her. In Sussex doctor Tim Finch faces an accusation by patient's daughter Alison Pinion and television host James Hollis searches for his missing son Elliot in London. Meanwhile struggling salesman Pete Carr is finding it difficult to make ends meet for his family and in Bristol artist Chris Lowe makes a marriage proposal. One of these men will have a connection to the dead girl Hayley Reid.