The Ninth Circle has been tempting me for a while now, and it's just clamoured itself to the top of the pile (that I was restacking anyway).
From the Blurb:
A man comes round on the floor of a shabby flat in the middle of Budapest. His head is glued to the floorboards with his own blood. There's a fortune in cash on the kitchen table. And he has no idea where, or who, he is.
He can do extraordinary things - speak any number of languages fluently, go three days without food or sleep, and fight with extraordinary prowess. But without a name, without a past, he's isolted from the rest of the world; a stranger to everyone, including himself - until a chance encounter with a young scholar leads to his first friendship, and his first hint that someone out there knows more about him than he does.
My name is Gabriel. There - I have a name. So there's no need to be afraid. But I wish I could remember ... something more.