Fearless nine-year-old "Scab" McNally tries to get his twin sister's help in convincing their parents to let them get a dog, but when he embarrasses her in school with a particularly obnoxious invention, it looks like he has lost her cooperation forever.

Twelve-year-old Cruz Coronado leaves his home in Hawaii to study and travel with other young people invited to attend the elite Explorer Academy in Washington, D.C., but a family connection to the organization could jeopardize his future.

"Cruz and his fellow recruits tackle challenging missions to dispense life-saving medication to gorillas, thwart pangolin poachers, and capture images of the last known cheetahs in Namibia--all the while discovering that protecting the world's threatenedspecies is a dangerous business. Things turn deadly for Lani, Sailor, Emmett, and Cruz as they search for the fourth piece of Cruz's mom's cipher. Cruz knows it's not going to be easy, but will an...

"Cruz Coronado sets sail for the shores of Iceland and Norway aboard the Explorer Academy ship to continue his studies at sea. But, things take a turn while exploring the icy north, when he embarks on a dangerous mission to uncover the first piece of an important puzzle his mother left behind"--