San Sebastian, 1954: Comandante Guzmán, Franco's one-time favourite secret policeman is out of favour and exiled to the Basque country. Guzmán was last here during the war, heading a platoon of bloodthirsty irregulars. He'd rather forget that. But, up in the hills, he'll find he hasn't been forgotten at all.

Madrid, 2010: Forensic Investigator Ana María Galindez has been sent to the Basque country, where three skeletons have been found in a sealed cellar. In the debris surrounding them she finds a scimitar, stamped with a name: Capitán Leopoldo Guzmán.

Guzmán's name is the key to unlocking Spain's darkest secrets. But, as Galindez will discover, Guzmán's name is also a death sentence.

Mark Oldfield was born in Sheffield, but now lives in Kent. He holds a PhD in criminology.