Cephalopods get their turn in NATURE's spotlight, with underwater cameraman Bob Cranston diving alongside marine scientists to film squids, cuttlefish, octopuses, and nautili in the waters off Indonesia, Mexico, Australia, and Texas. The camera catches a giant Humboldt squid pack hunting off Mexico's coast, a species known for aggressive behavior toward divers, cannibalizing its own wounded, and flashing red-and-white light displays that researchers believe function as communication. In shallower water, the tiny blue-ringed octopus turns up as one of the most venomous animals in the ocean despite fitting in a hand. Cranston and the scientists work to explain how a boneless, short-lived animal manages behavior this complex, from color-changing skin used for camouflage and signaling to the split-second decisions of a beak strike. The film moves site to site rather than building a single narrative, using each location to add another cephalopod species and another piece of the argument that these animals think and react far faster than their soft bodies suggest.