Aigbert the Alchemist

Aigbert is an alchemist in eleventh century England, and he gets involved in a search for a kidnapped victim named Brom. With the help of a thirteen year-old local thief, and the daughter of Lord Thingfirth, who is disguised as a boy named Gilbert, he sets out to track down brom's last known movements. The search takes them to the castle of Althalos, who is secretly conspiring against the earl of Mercia, who is Lord Thingfirth's brother. Aigbert and his friends find that Althalos has Brom imprisoned in the castle, and report this to Lord Thingfirth, who with the earl set out to free him.