Roman Britain, AD 224

Quintus Valerius, imperial investigator, and his British option, Tiro, are sent to York to strengthen ties with the new legate of the Sixth Victrix legion, Marius Crescens.

In the depths of the northern winter, Saturnalia celebrations take over the streets – and a series of seemingly unrelated murders attracts the attention of Valerius.

The two soldiers are soon heading towards Hadrian’s Wall on the trail of Tribune Gaius Laelianus, suspected of the death of Placidia Septimia, the legate’s young wife. But Valerius, damaged by previous service beyond the Wall, mistrusts what he hears and sees.

Valerius has left behind in York his wife, Julia, who discovers that the murdered woman kept a journal detailing fears about her husband’s collusion with barbarians. But Placidia was silenced before she could talk, and the journal has disappeared.

Crescens’ men pursue the soldiers and their suspect to Vindolanda, where they narrowly escape. Fleeing further north to a deserted Tayside fort, Valerius and Tiro must fight for their lives to uncover the truth, and prevent the invasion of Britannia by a ruthless new enemy – the Picts.