After a sea battle between the Olympians and the Titans, the Olympians find themselves shipwrecked on an island, and when Uranus' stars falls into the ocean, a dangerous wave of bubbles heads towards the island.

After a sea battle between the Olympians and the Titans, the Olympians find themselves shipwrecked on an island, and when Uranus' stars falls into the ocean, a dangerous wave of bubbles heads towards the island.

Zeus and his friends try to free Briar, Kottos, and Gyes from Tartarus so they can finally beat Cronus once and for all in this Heroes in Training adventure. The fourteen Olympians and Ron are headed toward Olympus. Ron is telling them the rumors that the Titans have all escaped Tartarus and are gearing up with Cronus for a final battle with the Olympians. When they reach the sea, Oceanus attacks them by surprise. They are almost washed away by a tidal wave when mysterious woman appears and saves them. It is Gaia, the wife of Uranus—and grandmother to Zeus and most of the Olympians. Gaia is on the side of the Olympians, partly because she believes that they will be better for the planet than Cronus, but also because she is angry with her son. He has imprisoned his three brothers: Briar, Kottos, and Gyes. She says if the Olympians free them from Tartarus, they will help the Olympians defeat Cronus. But can the three brothers be trusted? And can the Olympians defeat Cronus once and for all?

When the Olympians arrive on the island of Lemnos, they meet the metal-working Hephaestus who is hesitant to leave with the gods, stating that the only way he will join them is if he gets to be their leader.

Zeus and his fellow gods-in-training attempt to capture the king of hell’s hound in this latest Heroes in Training chapter book! Zeus and his fellow gods-in-training face a new challenge in the underworld when they attempt to capture Cerberus—the three-headed guardian and cherished pet of Zeus’s brother Hades. But they find themselves up against even more than they anticipated when they have to face off against Melinoe and her skeletal minions.

When ten-year-old Zeus is kidnapped, he discovers he can defend himself with a magical thunderbolt.

The Heroes in Training are entering the Underworld—if Hades can conquer his canine fears, that is. The Underworld usually isn’t really meant to be a fun place—but tell that to Hades! He loves the dark and the stinky smell of sulfur. However, there is one thing that Hades is not a fan of: dogs. And when Zeus and his fellow Olympians encounter Cerberus—a snarling, three-headed dog—Hades must conquer his fears and tame the hound so everyone can continue into the Underworld and deposit their Titan prisoner, Oceanus, back where he belongs! But with magical water that causes forgetfulness, hot beds of lava, and another epic battle with two more Titans standing in their way, will Zeus and his heroes make it out of the Underworld with everyone intact?