The Island is the second book in the Museum Mysteries series. Kimberly, Claira, and Ariel met Bast, a mysterious black cat, on their first adventure in The Portal, book one of the series. Bast has returned, along with her friend Maximus, a large black Labrador with a bionic eye, to ask them to go on another adventure. A young girl is shipwrecked on an island and needs their help. Will they agree to enter the secret portal in the wall closet with Bast? Who is the girl and why is she on the island?