Secrets and Ciphers

Someone has been sneaking into the tree house.

When Sarina and Ezzie, a pair of twins with a penchant for trouble, move to Panama, they get a lot more than they bargained for.

A stepfather with a shadowy past.
A mysterious stalker, always watching.
A whole lot of disappearing children.
And then, someone hiding in their tree house.

And he might be in danger.