Erak's Ransom

Erak, the Oberjarl of Skandia, has been captured by a desert tribe far south of any map the Araluens keep. The ransom is enormous and the deadline is short, and the party the King sends to pay it — Halt, Gilan, Horace, Princess Cassandra, and a still-apprentice Will — is going to have to cross a desert no one in Araluen has ever seen to get there.

Erak’s Ransom was published as the seventh book, but Flanagan wrote it as a look back at the missing year between the end of The Battle for Skandia and the start of The Sorcerer of the North. Will is still an apprentice here; his graduation is part of the book. Many longtime fans read it between books 4 and 5 for that reason. Published order works too — the book is largely self-contained.