It's the world's oldest secret....... ...., and the world is about to find out Covenant of Silence David Hallet is awaiting trial for the murder of Nelson Kosoto, who is suspected of killing Hallet's daughter. He clearly had a motive and his DNA was found at the crime scene, a house that Hallet denies ever visiting. He has no alibi but the murder weapon has never been found. The murder squad and the CPS are confident of a conviction until H division arrests someone else for the same murder. The case against Hallet is collapsing and forensic officer Cally Boyce is suspected of planting DNA evidence. Cally's boyfriend, Tyler Watson, is a brilliantly talented molecular biologist. His own work begins to cast doubt on the reliability of the DNA evidence as a dark, underlying conspiracy begins to reveal itself. Cally is convinced of David Hallet's innocence and that, in Leroy Livingstone, H division has the real killer. But, just when a confession by Livingstone secures the release of the original prime suspect, Cally begins to doubt her own judgement. A chance telephone call leads to a meeting with a member of Livingstone's gang, who convinces her that Hallet may, indeed, be the killer. Meanwhile, Tyler's own work with DNA is in danger of undermining Cally's investigation, but it is leading him towards a dark secret, hidden in the depths of time. It's the world's oldest secret - and the world is about to find out. Can Cally and Tyler break the Covenant of Silence?