Andrea Schlake volunteers at an animal sanctuary when a chimpanzee escapes its enclosure and chases her down; a great white shark knocks surfer Todd Endris off his board and attacks him.

Jim Lane picks blueberries alone in the Blue Ridge Mountains until a timber rattlesnake attacks; teacher Rachael Lilienthal's swim in a Florida river becomes a struggle when an alligator bites down on her arm, pulls her underwater and doesn't let go.

A grizzly bear charges taxidermist Wilf Lloyd while he hunts elk with his son-in-law in the Canadian Rocky Mountains; miles from shore, diving 180 feet below the surface, spearfisher Anthony Segrich finds a bull shark charging toward him.

A polar bear chases down Erin Greene as she walks home from a Halloween party in a small arctic town; a bull shark attacks triathlete Chuck Anderson in the Gulf of Mexico, biting his arm and pulling him to the ocean floor.

Diver Tim Saxon films underwater at the Great Barrier Reef and gets stung by an Irukandji jellyfish, one of the world's most venomous animals; a grizzly bear attacks forester George Knoll in the remote Great Bear Rainforest.

A black bear charges Joe Azzouggagh and his German shepherd, Ace, deep in the Ontario wilderness; single father Andrew Dickehage, forced to walk six miles along a rural road at night, comes under attack from unseen predators.