Ethan and Matt receive a call for help from Lisa Moser, whose mom runs the “Skywalk Zoo”. Recently, the animals at the Zoo have been taking turns in behaving weirdly and aggressively, scaring visitors away. The police are no help and if Lisa doesn’t figure out why it’s happening, the Zoo will be shut down and the animals put to sleep...

As Ethan and Matt are local celebrities after solving the mystery of the legendary missing diamond Heart of the Island, Lisa wants their help. With Lisa as their first client of their newly set up detective agency Project Adventure, Ethan and Matt head off to the Zoo. They have the weekend to solve the mystery of why the animals behave so strangely. The boys meet Lisa, and after discovering a chilling fact, forge a daring plan to get to the bottom of this mystery. But their search for the truth draws them deeper into this deceit and betrayal filled adventure.

Will they find out why the animals behave so strangely? Can the boys find out who’s behind all this? And can they protect the animals and stay safe? Could Lisa become more than just a first client, and join the boys on their adventures....? Find out what happens in this nail biting adventure at the Zoo, full of wild animals and rotten villains.