An explosive revelation and a familiar face heighten the mystery for Cruz and friends in the sixth book in this adventure-packed series. Still reeling from the life-changing discovery he found buried in the mysterious archive, Cruz Coronado grapples with an important secret as the gang heads to China in search of the second-to-last piece of the cipher. Under the watchful eye of a new adviser, life on the ship returns to almost normal...Almost. Just as things seem to be going smoothly, a familiar face shocks Cruz back into reality, and the final piece in this life-and-death scavenger hunt veers toward a dead end. Explorer Academy features: Gripping fact-based fiction plot that inspires curiosity with new technology and innovations; Amazing inventions and gadgets; A cast of diverse, relatable characters; Secret clues, codes, and ciphers to track down within the text; Vibrant illustrations, Elements of STEAM; National Geographic explorer profiles in The Truth Behind Section. Complete your collection with: The Nebula Secret (1) The Falcon's Feather (2) The Double Helix (3) The Star Dunes (4) The Tiger's Nest (5) Explorer Academy Code-Breaking Adventure Explorer Academy Ultimate Activity Challenge Explorer Academy Field Journal Explorer Academy Future Tech.