Ибн Фадлан
The novel is set in the 10th century. The Caliph of Baghdad, Al-Muqtadir, sends his ambassador, Ahmad ibn Fadlan, on a mission to assist the king of the Volga Bulgars. Ahmad ibn Fadlan never arrives, as he is conscripted by a group of Vikings to take part in a hero's quest to the north; he is taken along as the thirteenth member of their group to comply with a soothsayer's requirement for success. In the north, the group battles with the 'mist-monsters', or 'wendol', a tribe of vicious savages (suggested by the narrator to have been possibly relict Neanderthals) who go to battle wearing bear skins.