Now with a reimagined look! Set sail to Atlantis with Tim and his friends in the laugh-out-loud funny, highly illustrated fourth book of the New York Times bestselling Once Upon a Tim chapter book series from Spy School author Stuart Gibbs.

Tim and his ragtag crew have been rescued from certain doom by a mermaid princess—but now, she wants something in return for saving their lives: her father King Neptuna’s stolen trident.

To pay their debt, Tim, Belinda, Ferkle, Rover, and Princess Grace once again brave the Sea of Terror to track down the trident in the glorious city of Atlantis, which hasn’t sunk into the sea yet. (In fact, it is famed as the safest city on earth.) But there is plenty of danger en route—and the notorious Prince Ruprecht is lurking about as well. Can the junior knights evade the scheming royal and complete their quest?

Stuart Gibbs is the New York Times bestselling author of the Charlie Thorne series, FunJungle series, Moon Base Alpha series, Once Upon a Tim series, and Spy School series. He has written screenplays, worked on a whole bunch of animated films, developed TV shows, been a newspaper columnist, and researched capybaras (the world’s largest rodents). Stuart lives with his family in Los Angeles. You can learn more about what he’s up to at StuartGibbs.com.

Chris Choi is an illustrator, author, and graphic novelist who formerly worked under the pseudonym “Chris Danger.” Chris, an army brat, lived everywhere, but grew up mostly in Hawai’i. He attended the School of Visual Arts in New York City, worked in animation and academia for a few years, and has been a full-time freelance illustrator for almost a decade now. He currently lives in Philadelphia with his wife Eva and their dog and two cats. Visit him on Instagram @Choi_Meets_World.