Word of Honour (The Laws of Magic Series #3)

Aubrey and George struggle to concentrate on their studies amidst mysteries, secret adversaries, and deep undersea adventures
 
Magical genius Aubrey Fitzwilliam, along with his loyal friend George, is trying to immerse himself in his new life at college. But for Aubrey life is never straightforward. When Aubrey's father, the Prime Minister, invites them to take a ride on a top-secret submersible, Aubrey and George can't resist. But a sudden magical attack threatens to send them to the bottom of the ocean and begins a whirlwind series of events—a plot to rob Albion's largest bank, strange underground disturbances, and an opera singer who bears an uncanny resemblance to Aubrey's nemesis, Dr. Tremaine.