In a gripping tale spanning seven decades and three continents, the story of a strange ring unfolds and with it the story of the people whose lives will be irrevocably changed by owning it.

The mystery begins with the unsolved murder of historian Dr Charles Gibson at his home in Edinburgh. Meanwhile, two thousand miles away in Rome, a passionate love affair ends in ignominious dismissal for former British diplomat Angharad Wilson when her lover is exposed as a field operative for the Iranian Intelligence Services.

Exonerated from a potential charge of treason but not reinstated Angharad is unemployed. Caught in the lining of a coat she buys from a charity shop she finds an ugly but clearly valuable gold ring. Her search for the owner will take her from Edinburgh's New Town to Istanbul.