The Plague of God - Sente Carlo F.

A contemporary adventure, a 9th century epic of intrigue, murder and greed, the plots connected by the power gold holds: 

Forced to sell the family property, a baron in present-day Germany succumbs to the whispered promise of a fabled treasure and sets out on a dangerous quest ...

Centuries earlier, the same lure of treasure leads a Viking shieldmaiden to the dark forests of Eastern Francia where she realizes the terrible mistake she's made in following a merciless warlord ...