THE NEXT DAY, it's my turn to get wet. I remind myself that Cassell is still alive after hundreds of dives, but it's hard to ignore two important qualifiers. First, he's a much more skilled diver. And second, he's a hell of a lot tougher.

I try to channel Gilly, but instead I feel like I have KERSTITCH emblazoned across the back of my wetsuit as we motor out early in the afternoon. Today, there's a building breeze, and the sea surface is choppy, which will reduce visibility. Still, we gear up (I also pass on the unfamiliar squid armor after getting assurance from Cassell that he'll watch my back) and drop into the water as soon as Rafael finds the squid shoal. No matter what happens, I tell myself, do not let your regulator get yanked from your mouth.

Cassell escorts me down to about 45 feet and clips one of the restraining wires to my scuba backpack. I settle in and take a look around. The rays of sun shafting into the depths give the water a greenish, hazy hue, so I feel as if I'm swimming in a light fog. There's a current running, and we're quickly strung out on the wires, making it difficult to maintain depth as Rafael starts hauling jigged squid from below us.

With the current, the poor visibility, the confusion of wires, and a barbed jig whizzing up from the depths (Cassell was once hooked in the chest, and even he admits that it really hurt), I forget for a moment to worry about gangs of squid. Instead,

The squid are all around me. Everywhere, ghostly shadows torpedo through the water.

I concentrate on staying clear of Cassell and Dale as they set up beneath the boat and making sure I don't get hooked by Rafael. Slowly I notice that the squid are all around me. None of them decide to take the rookie for a ride or even move in for a tentacular taste test. But everywhere on the periphery of my vision, ghostly shadows are torpedoing through the water. Their speed and agility is mind-blowing, and every once in a while one will suddenly eject a cloud of rust-colored ink into the water. Cassell later explains that the squid mix mucus with the ink, which allows them to give the burst a squidlike shape to fool predators. He then shows me a video sequence filmed that day in which a jigged squid inks just as a cannibal is rushing in and dupes the attacker into hitting the cloud.

I see a jig rising past me, and the hooked squid is flashing red and white like a neon sign. It's a stunning display, and another extraordinary aspect of Humboldt squid behavior. Both Cassell and Gilly believe that the squid use the flashing (which is enabled by millions of chromatophores in the skin that can be opened like little umbrellas to show red or closed to show white) to communicate with one another, though they've deciphered none of the "language." The effect is so dramatic you can almost feel the squid's emotion being transmitted through the water. In this case, it appears to be fear—or at least a vain plea for mercy. Because as the jigged squid goes past, I can see a pack of four-foot cannibals shadowing along, jetting in mercilessly and relentlessly to take quick bites of flesh.

When I eventually roll back into the boat untouched, the brief experience has already started to transform the squid in my mind from a fearsome unknown into an astonishing example of evolutionary design. On the way back into Santa Rosalía, I start to wonder whether all the talk about red devils and killer squid is more creative marketing than reality. When I spoke with underwater cinematographer Bob Cranston, he admitted that nature television likes to exaggerate the dangers of the Humboldt squid. "There's a lot of hype," he said. "But I empathize with Cassell. We've all got to make a living."

I voice my doubts to Cassell. "Well, we've just been in with the babies," he says. "You really need to see the big guys." I ask whether he has film of his deep encounters with the six- and seven-foot "rogues" and "giants" he likes to talk about and whether he can send me clips of his hairiest confrontations. I like the idea of monsters abroad in our risk-managed, hyper-conditioned world, but now I want to see proof.