Over one million British Empire soldiers were killed during the First World War. More than a century later, over half a million still have no known grave.

The scale of the fighting, the catastrophic destruction, the relentless military engagement and glutinous mud meant that many of the dead were never identified, of often, never recovered. Names were left without bodies, and bodies, or fragments of bodies, without names.

To help staunch the tide of national grief in the aftermath of the conflict, an idea was born for a single 'Unknown Warrior' representing all the missing, to be brought from the battlefields and buried in Westminster Abbey alongside the nation's kings and queens.

Using diaries, archives and interviews with the descendants of that generation and modern-day experts, Sunday Times bestselling author and former RAF Tornado navigator John Nichol draws on his own experience of combat and loss to shine light on this 100-year-old story. And in speaking to those who have lost loved ones in more modern conflicts, he examines our continuing need for a tangible resting place at which to truly grieve the fallen.

His search for answers becomes a moving and personal journey, exploring the true meaning of camaraderie, service, sacrifice and remembrance.