S1, E3: Known for their boundless grace and playful energy, captive dolphins are always eager to please and perform. But at home in the open sea, there's another little-known side to these awe-inspiring mammals that's powerful, cunning, and ruthless. Witness as a team of dolphins coordinates a devastating attack on a massive school of fish. See the largest, most fearsome member of the dolphin family-a killer whale-that can travel as fast as 30 miles an hour underwater to capture its next victim. Observe as dolphins learn from an early age how to hydroplane through mere inches of water to catch fish. You'll be amazed to explore the secret side of these sociable yet aggressive creatures.