Eve of the Emperor Penguin by Mary Pope Osborne

Jack and Annie journey to Antarctica to search for the secret of happiness—and find themselves in the freezing cold surrounded by penguins, researchers, and a hidden world beneath the ice. As they uncover clues, they descend into an ice cave and discover an ancient magical library. Facing avalanches and icy danger, they must rely on trust and instinct to survive. The story mixes real-world survival with ancient mystery. It’s a chilly quest filled with surprises and heart.