Nick and his friend Marta decide to investigate when a mysterious fire starts near a Florida wildlife preserve and an unpopular teacher goes missing.

Rick, a fourteen-year-old foster child, escapes from a juvenile detention facility near Las Vegas and travels to Canyonlands National Park in Utah where he meets a bird biologist working on a project to reintroduce condors to the wild.

While on a hike through the Amazon rain forest, Lea confronts piranhas and anacondas, but when she comes across an injured baby sloth, she must decide whether or not it is right to try to save it.

"There are no polar bears left on Bear Island. At least, that's what April's father tells her when his scientific research takes them to a faraway Arctic outpost for six months. But one night, April catches a glimpse of something distinctly bear shaped loping across the horizon. A polar bear who shouldn't be there--who is hungry, lonely, and a long way from home. As their unlikely bond grows, April is determined to save her new friend--and so begins...

After a summer of tagging sharks off the west coast of Florida, Sabina, Maribel, and Luke have a new assignment: searching for "survivor trees" that are resistant to the disease that is destroying the state's citrus trees; the search takes them to the remote mangrove islands of Sanibel Island, where they discover Spanish oranges, a grave, an immense saltwater crocodile, a reclusive woman who believes that the ghost of a dead king, beheaded by Spanish...