Something strange is going down in the sleepy seaside village of Madderly Bay. Best friends Selena and Chloe are stuck in the most boring summer ever—until food starts coming to life and running wild in the streets.

But that’s just the beginning. Earthquakes start shaking the village, and creepy claw marks show up, hinting at something dark stirring beneath the waves. Only Selena and Chloe know the real story about the zombie mermaids they faced before—and now they’re worried the threat they thought was gone might be back.

As the tremors get worse and the water turns a scary green, the girls have to figure out what’s awakening in the depths before it’s too late. With their friend Zelda and her magical squid, Glowella, by their side, they’ll risk everything to save both the human and magical worlds from a danger that could destroy them all.

In this thrilling adventure, Selena and her friends have to face their fears and dig up some serious secrets between the human and magical worlds. With their village and the ocean in danger, the stakes couldn’t be higher. Can they figure out what’s messing with the sea before it’s too late? Or will they realize that saving their town—and both worlds—might be way harder than they thought?