The Salvager's Quest and The Call of the Right Whale - Lucy Hawkins

Stella and Dot are no ordinary sisters. At fifteen and thirteen, they captain The Salvager; a daring pirate ship on a mission to save Earth's endangered animals and transport them to the extraordinary Planet Beatrice, where woolly mammoths thunder across the plains and children make the rules.

Their latest quest takes them to Boston, where they dive into the cold Atlantic to track one of the rarest creatures on the planet: the North Atlantic right whale. But the ocean is full of threats-pollution, massive ships, and the constant risk of being too late.

As if that weren't complicated enough, Stella finds herself caught between two brothers: River, who's followed her to Earth, and Ace, the mysterious boy waiting for her back on Planet Beatrice.

The ocean is treacherous. The stakes are rising. And for Stella and Dot, every dive into danger forces them to ask the hardest question of all: what kind of future do they want-for Earth, for Planet Beatrice, and for themselves?