Upon doling out this lie, he gave Astrid a look that said: I know, I know. But how am I to account for why we haven’t returned a priceless artifact to the yacht’s owner?

And she gave him a look in return that said: I am absolutely, positively crazy about you and don’t give two hoots about what you tell them.

And in answer to that, Bo gave Astrid’s legs a bold perusal that sent a quick thrill through her chest.

Unaware of their silent communiqués, Dr. Navarro studied the idol, turning it over carefully before giving Mathilda a turn. They looked it over for a long time, and when they were both done murmuring small exclamations and pointing things out to each other in Spanish, Dr. Navarro took off her glasses and smiled up at Bo and Astrid. “Hadley was correct, as usual. This piece was certainly made in a style that was common in the fifteenth and sixteenth centuries.”

“Teoxihuitl is what the Aztecs called turquoise,” Mathilda added. “It’s a Nahuatl word that means ‘stone of the gods.’ It was used in special religious and ritual items, and no one was allowed to wear it as casual jewelry, like they do today. That would have been sacrilege. Therefore, this is not an everyday object.”

“Do you recognize the figure?” Bo asked.

“I believe it’s meant to be Ometeotl, who is a little mysterious. Many believe he was a supreme creator deity with a dual nature not unlike the Holy Trinity. Other scholars think he has been confused with another earlier god who makes life from bones—the Bone Lord, he was called. In fact, I wouldn’t be surprised at all if we’d find a bone armature beneath the turquoise, were we to remove it.”

“Someone has already altered it,” Bo pointing toward the word “NANCE.”

“Yes, that is a disgrace,” Mathilda said, shaking her head. “No museum will buy it, of course. And I’d wager that’s someone’s name. Names have great power. Tell them, Maria.”

Dr. Navarro stretched out her legs and lay back against her chair, pulling her shawl over her arms. “When Mathilda and I lived in Mexico City, we occasionally heard a legend from other anthropologists about a group of royal soothsayers who advised the Aztec nobility for almost two hundred years. They weren’t native. They were said to have come from a foreign land—where, exactly, was unknown. But the interesting thing about them is that they supposedly performed a secret ritual once every decade in order to extend their life.”

“Immortality?” Astrid said.

“More like . . . a Fountain of Youth to give them extra time,” Mathilda explained. “It was a ritual performed over water—over Lake Texcoco, which was the home of the Aztecs. They established their empire on an island in the middle of that lake. Mexico City was later built on top of it, and the lake was drained.”

Ritual performed over water. Astrid thought of the Plumed Serpent.

“And how is this legend connected to our idol?” Bo asked.

Dr. Navarro leaned closer, as if someone might overhear them, and spoke in an exhilarated tone. “Because the soothsayer’s ritual involved the use of ceremonial turquoise idols purported to be very much like this.”

“Very much,” Mathilda agreed.

Bo frowned at the idol, and Astrid wondered if he was thinking about the ritual in her vision. She certainly was. “Would this ritual also have involved human sacrifice?” she asked.

Dr. Navarro shrugged. “Perhaps. Sacrifice was common in pre-Columbian cultures. They believed life was cyclical—birth, death, rebirth. Death was not the end of life, but part of it.”

“Your Viking ancestors were known to sacrifice a few souls themselves,” Mathilda said to Astrid. “And your Chinese ancestors, too, Mr. Yeung. We are all descended from barbarians.”

“Barbarians and lovers of grandiose drama,” Dr. Navarro said “The Mayans sometimes anointed their sacrifices’ bodies with blue pigment and shot them through with arrows.”

Blue pigment . . .

Excitement made the hairs on Astrid’s arms rise. The yacht survivors were performing a ritual to extend their lives. The people she’d seen in the burlap sacks were human sacrifices. Sacrifices! Could this really be possible in this day and age, here in San Francisco?

Dr. Navarro pointed to the idol. “All of that aside, the symbol on the front is not Aztec. It’s not Central American at all, which is very odd. If we entertain the notion that this actually might be one of the ceremonial idols used by the soothsayers of legend, then perhaps it is proof that the soothsayers were, indeed, foreigners.”

When pressed, neither woman had a guess as to the cultural origin of symbol on the golden disk. Its style was both too generic and, at the same time, unique enough for them to rule out anything either of them had seen before.

Which was utterly disappointing.

“Is it possible the entire idol isn’t Aztec at all?” Bo asked.

Dr. Navarro shook her head. “I say at least most of this is genuine, and the style matches other known turquoise work from that period.”

Mathilda gave the idol another close inspection. “In the legend, the soothsayers died off when their ritual idols were stolen. I suppose they did not see the future very well that day,” she said with a mischievous smile.

Dr. Navarro snorted. “They must have been terrible oracles altogether not to see the Spaniards coming nor the outbreak of smallpox that would ravage the Valley of Mexico.”

“You said the idols were stolen,” Bo said. “Stolen by whom?”