In this suspenseful sequel to The Sailor Cipher, Sailor York must learn to control her extraordinary ability to communicate with animals to save her sister--and the planet.

The deadly animal-smuggling ring Hydrus is at it again: They've created a high-tech device that lures animals to be captured and sold. Sailor and her Explorer Academy friends Lani, Cruz, and Emmett--aka the Vela Squad--are determined to stop Hydrus at any cost. Their secret weapon? Sailor's mysterious powers, which she is still learning how to use, all the while juggling their most challenging semester at Explorer Academy yet! To add to the pressure, it's not just animals' lives at stake, but the life of Sailor's missing sister, Keel. Following a trail of clues around the globe leads the Vela Squad to an astounding discovery and daring race against the clock. In the end, their courage--and everything they thought they knew about Explorer Academy--will be put to the test.