The Madre de aguas of Cuba

"In Cuba, it is believed that a mysterious water serpent-- the Madre de aguas-- is responsible for providing and protecting the fresh water of the island. But the serpent is missing, and a drought has gripped the island. Uchenna, Elliot, and Professor Fauna fly to Cuba and endeavor to rescue the Madre de aguas. Unfortunately, it tries to kill them. Meanwhile, the Schmoke Brothers' goons are driving around Havana, dumping pink sludge into the sewers"--Amazon.