Tunnel trouble

Ava and her friends are determined to learn everything they can about the curios left by her Great-Aunt Enid, and to make sure the magic doesn't break free and cause chaos again. But when a strange figure is seen roaming the rooftops and Lily's five-year-old sister Mai insists that a monster is visiting her, it looks like the girls (and Ava's Tibetan terrier, Pepper) have another magical mystery to solve.