Nico had survived being trapped in a jar with 8 pomegranate seeds. He'd survived losing his sister. He'd even lived through Tartarus. But one thing he wasn't going to survive was Leo's giant fire-breathing dragon head.

Even though Leo had said he was 'fixing its motor system', Nico couldn't see how. All Leo was doing, it seemed, was poking it with a stick. Plus every time Happy the Dragon creaked, he jumped. Right now, he was dodging the flames that came from its mouth. They'd laughed at him for being terrified of a fake dragon (although Leo would kill anyone who called it fake) and not of normal things, such as the Furies.

Whatever. He was the son of the god of the dead. And besides, how was it normal to be scared of Furies?

They had been stuck, hovering over the Mediterranean for days. The ship had broken down, and this time they didn't have the lime, tar and celestial bronze to fix it. Frank had been sent (as a large bird) along with Hazel (or Miss Metal Detector, as Leo called her) to search for the bronze that morning. And Jason and Piper still hadn't returned from their quest for the lime and tar, despite having been sent since this morning. He wasn't worried, though. No, he had much more important things to worry about.

Like the fact that Percy and Annabeth had fallen into Tartarus.

Just hearing the word made him feel sick and dizzy, like he'd been hanging upside down. Nico shook his head, trying not to think about it. He was supposed to be reading Archimedes' scrolls anyway (although he wondered why Leo trusted him on this job).

The strains of Coach Gleeson's TV show floated into his ears. He was watching a blockbuster, he realized. Nico wondered why, after all they'd been through, he could still do that. In the last couple of years, he'd gotten frustrated watching those. Their problems were so simple, so easily solved…well, compared to his, they were. In the movies, they all knew everything was going to go well; they were going to save the day. On this quest, part of the seven now that two had disappeared, he always felt that his life was on the line. And it was.

A loud crash suddenly brought him back to the present. Frank and Hazel landed on the deck, Hazel carrying a long, rusty celestial bronze sword and shield. Leo ran over to intercept them, as Frank turned human again and ended up being hit on the back of his head with Frank's bow. Nico caught Leo shooting Frank a dirty look, like, man, was that on purpose?

"Nico, get under!" cried Hazel. "They're coming!"

Nico appeared confused. "What? No way. I'm not just going to go to take a nap while you guys battle monsters!" Jeez, what did they think he was, some kind of invalid?

All right, he had been, until today, really. But seriously, if he left them now, it would be really selfish. They were all in this together.

In the distance, he could see - were those Sirens?- flying towards them. They cawed, sounding more menacing than melodic, like they were supposed to be. Their ugly faces were carved into expressions of anger.

'What are they doing here?" Leo said, sounding panicky. The Sirens never left their island, as far as he knew. Their job was to sit and sing, luring sailors into their arms.

"I don't know!" said Hazel. "We were flying over the Mediterranean, and I sensed some celestial bronze, I guess from some shipwreck ages ago. Then – Frank saw them. The Sirens, I mean."

"You can give us the story later! Leo, have you got any wax?" Nico interrupted, over the din of the cawing Sirens. Leo shook his head in reply.

"Don't worry! They're not going to sing!" Frank said, getting into stance. "I don't know why, but it's like they've been ordered not to or something. Their job is to capture us without killing us, I think."

They were closer now. Nico drew his blade to Stygian iron, his face turning hard.

He knew Percy and Annabeth had survived these things on their quest to get the Golden Fleece. He hadn't been there, but others had told him about it, how they were two of the few heroes that actually (somewhat) defeated the Sirens. But that wasn't going to help now, since the only way they escaped the spell was going underwater where the sound didn't travel as well.

There were 3 of them, Pisinoe, Aglaope and Thelxiepy. Nico knew them well because they'd been turned into these horrible creatures by Demeter when they'd failed to save Persephone, his stepmother. Before that, they had been her handmaidens.

The realization dawned on him. Was it possible they were working for Gaia, now? It was very possible, considering they hated Demeter. And why else would they not sing or leave their island?

Oh, son of Hades, my pawn. That's right. They're working for me. They may have failed in their job before, but now, their need for revenge is stronger. They'll bring you to me, my dear sacrifice. The two of you.

The voice was so sudden Nico whirled round, expecting her to appear. He could imagine the large, sleepy face, with that tiny smile of hers. Of course, there was no one. They were floating, after all. This wasn't Gaia's territory.

Before he could try to think of what she meant, the Sirens descended on them.

The four of them went into fighting mode. Leo lit his hand on fire, careful not to touch Frank or Hazel, and burnt one of the Siren's wings. Nico started slashing at every part of it, and willed it to die (although this never helped). Hazel tried to stab them with her cavalry sword, and Frank turned into a grizzly (again. He'd done this before, although Nico hadn't been present. Hazel had told him about it, though.) One of the bird's claws missed Nico's face by an inch. In the back of his mind, he wondered why Coach Gleeson hadn't arrived, brandishing his club and yelling, "Die, bird scum!" And where was Festus's fire-breathing ability when they needed it?

"Hey, Birdbrain! Didn't you drown yourself when you couldn't kill Odysseus? What are you doing here alive?" shouted Leo, trying to distract them (that was usually Percy's job, Nico thought).

The largest Siren snarled (which sounded rather weird coming from a bird). "Don't you know, foolish boy? We are monsters, and we came back. And now, we fight for the Earth Mother! We unite, all the haters, the giants, and prepare to overcome the Olympians! You, with your silly games, will never stand a chance!"

Nico ducked another talon, and aimed for the bird's neck as it swooped down to attack Hazel. "We're friends with Percy and Annabeth!" called Frank, in an attempt to scare them. "Don't you know them? They escaped you 4 years ago. Well, they're coming now, to help us!"

The other one, attacking Leo, laughed. "Your friends? Oh, we know them well. They're stuck in Tartarus, fighting for their lives at the moment. They'll never live, and become Gaia's sacrifices!"

Nico's heart lurched. Not Percy and Annabeth. Not them. It couldn't be them. They had saved him and…and Bianca, all those years ago. Percy had saved him just last week. He couldn't let them die.

Taking advantage of how Nico seemed distracted, the bird made a large gash in his arm. Blood started pouring out. Nico returned it by stabbing the side of the Siren. After it hit him over with its wing, he thought the fight had gone on too long. Summoning all of his energy, he cut its head off cleanly. It crumbled to dust. At the same time, Leo burnt the last part of the bird he'd been trying to kill. Now, the largest one looked scared. Nico knew what would happen before it did.

"Cover your ears!" he yelled, warning them. It didn't help.

Hazel crumpled to the ground and shut her eyes, putting her hands over her ears. Frank turned into a cobra. Leo lit himself on fire as a defense.

It started to sing.