Thane squints into the sun as he looks around at all the threes.

Gretchen frowns, like she’s still not one hundred percent convinced this is the right spot. I am.

“You have to admit,” I say, “a lot of the criteria make sense. There can’t be many places in the city that fit all of those things.”

“Especially the weeping muses.” Greer points to the carved women on the structures across the pond. “That feature is quite unique.”

Gretchen clenches and unclenches her jaw.

“They’re right,” Nick says. “This has to be the spot.”

“If that’s even what the riddle is talking about.” She considers it for a moment and then shrugs. “It can’t hurt to look. Let’s split up.”

We agree to separate, to split up so we can search the area more thoroughly and quickly. Hopefully by the time the gorgons arrive from wherever they are, we’ll be ready to open the door. Greer stops us.

“One thing,” she says, leaning in close to whisper. “If you find it—or think you have—don’t draw attention to the location. Let’s meet back here when we’re done searching.”

Her voice is strained, like she’s worried about something.

“What’s wrong?” I ask.

“Nothing, I—” Greer looks over her shoulder, like she’s expecting someone to be eavesdropping on us. Considering how many people are trying to control the outcome of this war, it wouldn’t be a surprise. “I got a couple of weird texts earlier, and I think maybe . . .”

“We’re being watched?” Gretchen suggests.

“Yes.”

“I’ve been feeling it, too,” Gretchen says.

“I—” I want to say that I’ve noticed something, but I haven’t really. Maybe I’m just not as observant as my sisters. I whisper, “Then we’ll be extra careful.”

Gretchen volunteers to check out the parking-lot side of the Palace, the entire far side of the building that’s full of locked doors and service entrances, in case the door turns out to be an actual door, I guess. Nick goes with her.

Greer and Thane head off to the pond side of the building, the exterior rotunda and open-air porticos with lots of columns and great photo ops. It’s swarming with tourists trying—and mostly failing—to get pictures without anyone else in the frame.

Gretchen orders Sillus to go take a nap so he won’t slow us down. She sounds harsh, but I think she feels bad for him. He scrambles to the nearest empty bench and curls up in a tiny ball.

I get the lucky job of checking out the grassy areas and the open space around the eastern side of the pond. It’s a beautiful day, and I’m glad to be out in the sun. It almost makes me feel like I’m back in Orangevale. Not back home in Orangevale, because San Francisco is finally starting to feel like home. I wish Milo was here to enjoy the day with me.

There’s not very much to inspect on my side of the pond—a few trees, some benches, a tree-dense minipeninsula at one end. Lots of ducks and a pair of pristine white swans. Nothing that looks like a door, or even a door that’s not a door. It takes me only a few minutes to walk the entire length and back again.

I don’t notice any standout threes—I’m not counting the trio of seagulls that tried to chase me up a small hill. Nothing exceptional. Now what?

I sit down on the bench next to Sillus and stare out over the water.

The door is probably somewhere near the building anyway, right? The building has doors and archways and other door-like things.

Then what Sthenno said echoes in my mind: the door doesn’t look like a door. It’s a location—a certain place where, if my sisters and I open a portal, the door will appear.

Maybe I need to reorient my thinking. If we’re looking for a door that’s not a door, then the things that look like doors—the arches and actual doors—are less likely to be right.

As I survey the world around me, I run the third line of the riddle through my mind over and over again.

“Be three within three,” I mutter.

Three columns? Three benches? Three . . . I-don’t-know-whats.

Three within three, three within—

I gasp. “Three trees.”

It’s right there, right in front of me. As in directly in front of me.

Three gnarled and ancient-looking trees arranged in a triangular shape on a little piece of land that juts out into the pond just a tiny bit. They are tall, and their bark is almost black. Three within three. Three sisters within the triangle of three trees.

I quickly compare them to the other trees in the park. The rest look completely ordinary. There are none like them.

This has to be it.

Part of me wants to jump up and down, run over to the three trees—maybe hug them—and shout for my sisters to hurry up and join me. But I remember what Greer said about the weird texts, and what Gretchen said about feeling like we’re being watched. The last thing I want to do is draw attention to the door.

If anyone from the Olympic faction—Zeus, Apollo, or one of their many allies—finds out we’ve located the door before we’re ready, they won’t think twice about killing us to keep us from breaking the seal.

For all I know, one of their agents is somewhere here among the tourists, just waiting for a reason to strike.

Or someone from the monster side is hiding out nearby so they’re ready to attack the moment we open the door.