“I’m a bit puzzled,” Gamay said, subtly resisting the push of his guiding hand. “I’m sure I read on your website that you were doing research on other invertebrates. I haven’t seen any species of Cnidaria.”

The question seemed to catch Mayhew by surprise. He dropped his hand from her elbow and glanced reflexively at the door to a walled-off section of the lab.

“Jellyfish? Well . . .”

Mayhew may have been an accomplished scientist, but he was an amateur at cloak-and-dagger. Gamay’s eyes followed the direction of his revealing glance, and she gave him her most charming smile. Taking him by the arm, she urged him toward the door.

“I’ll bet you forgot,” she said.

“It’s not that,” he said. “It’s . . . We don’t like to disturb them.” He was folding under her unrelenting gaze. “Well, I suppose it won’t do any harm.”

He opened the door and ushered Gamay into a room that was dark except for the light emanating from a tall, cylindrical transparent plastic tank four feet across and eight feet high.

The light came from a dozen or so jellyfish, each about the size of a cabbage, that glowed with pulsating blue lights. They were in constant motion, moving from the bottom to the top of the tank in a graceful, hypnotic underwater dance.

A figure on a ladder, bending over the top of the tank, turned toward their interruption. The unearthly light revealed the face of Dr. Bennett, the toxicologist. She opened her mouth in surprise.

“Dr. Mayhew, I didn’t expect—”

“I leaned on Dr. Mayhew to show me this part of the lab,” Gamay explained. “I hope I’m not disturbing you.”

Bennett glanced at Mayhew, who gave her a nod.

“Not at all,” Bennett said with a halfhearted smile. She brandished the long-handled dip net in her hands. “This procedure can be a little tricky at times.”

Gamay’s eyes took in Bennett’s protective gloves and clear plastic face mask and coverall, and then she shifted her gaze back to the undulating, vaguely cube-shaped forms and their strange acrobatic ballet. Threadlike tentacles were attached to lacy fringe that rimmed each diaphanous creature. Their bioluminescence was almost bright enough to read a book by.

“In all my years of diving,” Gamay said, “I don’t think I have ever seen anything this beautiful.”

“Or as deadly,” added Mayhew, who had come up behind her. “The medusae in this tank produce a toxin that would put a cobra to shame.”

Gamay dug into her memory.

“This is a box jellyfish, isn’t it?” she asked.

“That’s right. Chironex fleckeri, the sea wasp. There have been almost one hundred recorded deaths from its sting, which can kill a human being in under three minutes. I suggest that we stand back and give Dr. Bennett some room.”

Dr. Bennett pulled the mask over her face and dipped the net in the tank.