Ansom, having been replaced as Chief Warlord, has suggested that he undertake diplomatic missions for his side.
Jack has expressed skepticism to their shared Mistress Wanda about Ansom's reliability as a diplomat, and has come to investigate his suspicions.
The Turnamancer is Vanna, a barbarian caster working for Faq, but being bankrolled by Charlie.
Ossomer was Ansom's brother, a Prince of Jetstone who was croaked and Decrypted at Expository Bridge (Book 2 Page 10), and who later was shamed into turning back to Jetstone. (Book 2 Page 73)