Invasion. Grumpy Old Wizards, #6

When Josephine joined the Earth Coalition and became part of the legendary White Knights, she thought she could leave the dangers of the world behind and raise her child within the peaceful sanctuary of Briodanis, an Ancient city protected by the most powerful magic the world has ever known. She couldn't have been more wrong. The White Knights have returned, but their power is greatly diminished, and their lives are in mortal peril.
As Josephine scrambles to understand her new abilities, she learns that a hostile AI from a distant world has discovered a way to travel to Earth. With a technologically advanced ship, the ruler of a vast and powerful army of androids will soon reach Earth, and the White Knights are the only ones capable of stopping the impending invasion.