Frank laughed. “Yeah, well…it’s harder than it sounds. We have to get past those scorpions and water cannons on the walls, fight through the inside of the fortress, find the banners, and defeat the guards, all while protecting our own banners and troops from capture. And our cohort is in competition with the other two attacking cohorts. We sort of work together, but not really. The cohort that captures the banners gets all the glory.”

Percy stumbled, trying to keep time with the left-right marching rhythm. Frank sympathized. He’d spent his first two weeks falling down.

“So why are we practicing this, anyway?” Percy asked. “Do you guys spend a lot of time laying siege to fortified cities?”

“Teamwork,” Hazel said. “Quick thinking. Tactics. Battle skills. You’d be surprised what you can learn in the war games.”

“Like who will stab you in the back,” Frank said.

“Especially that,” Hazel agreed.

They marched to the center of the Field of Mars and formed ranks. The Third and Fourth Cohorts assembled as far as possible from the Fifth. The centurions for the attacking side gathered for a conference. In the sky above them, Reyna circled on her pegasus, Scipio, ready to play referee.

Half a dozen giant eagles flew in formation behind her—prepared for ambulance airlift duty if necessary. The only person not participating in the game was Nico di Angelo, “Pluto’s ambassador,” who had climbed an observation tower about a hundred yards from the fort and would be watching with binoculars.

Frank propped his pilum against his shield and checked Percy’s armor. Every strap was correct. Every piece of armor was properly adjusted.

“You did it right,” he said in amazement. “Percy, you must’ve done war games before.”

“I don’t know. Maybe.”

The only thing that wasn’t regulation was Percy’s glowing bronze sword—not Imperial gold, and not a gladius. The blade was leaf-shaped, and the writing on the hilt was Greek.

Looking at it made Frank uneasy. Percy frowned. “We can use real weapons, right?”

“Yeah,” Frank agreed. “For sure. I’ve just never seen a sword like that.”

“What if I hurt somebody?”

“We heal them,” Frank said. “Or try to. The legion medics are pretty good with ambrosia and nectar, and unicorn draught.”

“No one dies,” Hazel said. “Well, not usually. And if they do—”

Frank imitated the voice of Vitellius: “They’re wimps! Backin my day, we died all the time, and we liked it!”

Hazel laughed. “Just stay with us, Percy. Chances are we’ll get the worst duty and get eliminated early. They’ll throw us at the walls first to soften up the defenses. Then the Third and Fourth Cohorts will march in and get the honors, if they can even breach the fort.”

Horns blew. Dakota and Gwen walked back from the officers’ conference, looking grim.

“All right, here’s the plan!” Dakota took a quick swig of Kool-Aid from his travel flask. “They’re throwing us at the walls first to soften up the defenses.”

The whole cohort groaned.

“I know, I know,” Gwen said. “But maybe this time we’ll have some luck!”

Leave it to Gwen to be the optimist. Everybody liked her because she took care of her people and tried to keep their spirits up. She could even control Dakota during his hyperactive bug-juice fits. Still, the campers grumbled and complained. Nobody believed in luck for the Fifth.

“First line with Dakota,” Gwen said. “Lock shields and advance in turtle formation to the main gates. Try to stay in one piece. Draw their fire. Second line—” Gwen turned to Frank’s row without much enthusiasm. “You seventeen, from Bobby over, take charge of the elephant and the scaling ladders. Try a flanking attack on the western wall. Maybe we can spread the defenders too thin. Frank, Hazel, Percy…well, just do whatever. Show Percy the ropes. Try to keep him alive.” She turned back to the whole cohort. “If anybody gets over the wall first, I’ll make sure you get the Mural Crown. Victory for the Fifth!”

The cohort cheered half heartedly and broke ranks.

Percy frowned. “‘Do whatever?’”

“Yeah,” Hazel sighed. “Big vote of confidence.”

“What’s the Mural Crown?” he asked.

“Military medal,” Frank said. He’d been forced to memorize all the possible awards. “Big honor for the first soldier to breach an enemy fort. You’ll notice nobody in the Fifth is wearing one. Usually we don’t even get into the fort because we’re burning or drowning or…”

He faltered, and looked at Percy. “Water cannons.”

“What?” Percy asked.

“The cannons on the walls,” Frank said, “they draw water from the aqueduct. There’s a pump system—heck, I don’t know how they work, but they’re under a lot of pressure. If you could control them, like you controlled the river—”

“Frank!” Hazel beamed. “That’s brilliant!”

Percy didn’t look so sure. “I don’t know how I did that at the river. I’m not sure I can control the cannons from this far away.”

“We’ll get you closer.” Frank pointed to the eastern wall of the fort, where the Fifth Cohort wouldn’t be attacking. “That’s where the defense will be weakest. They’ll never take three kids seriously. I think we can sneak up pretty close before they see us.”

“Sneak up how?” Percy asked.

Frank turned to Hazel. “Can you do that thing again?”

She punched him in the chest. “You said you wouldn’t tell anybody!”

Immediately Frank felt terrible. He’d gotten so caught up in the idea...

Hazel muttered under her breath. “Never mind. It’s fine.

Percy, he’s talking about the trenches. The Field of Mars is riddled with tunnels from over the years. Some are collapsed, or buried deep, but a lot of them are still passable. I’m pretty good at finding them and using them. I can even collapse them if I have to.”

“Like you did with the gorgons,” Percy said, “to slow them down.”

Frank nodded approvingly. “I told you Pluto was cool. He’s the god of everything under the earth. Hazel can find caves, tunnels, trapdoors—”

“And it was our secret,” she grumbled.

Frank felt himself blushing. “Yeah, sorry. But if we can get close—”

“And if I can knock out the water cannons…” Percy nodded, like he was warming to the idea. “What do we do then?”

Frank checked his quiver. He always stocked up on special arrows. He’d never gotten to use them before, but maybe tonight was the night. Maybe he could finally do something good enough to get Apollo’s attention.

“The rest is up to me,” he said. “Let’s go.”

XI Frank

FRANK HAD NEVER FELT SO SURE of anything, which made him nervous. Nothing he planned ever went right. He always managed to break, ruin, burn, sit on, or knock over something important. Yet he knew this strategy would work.

Hazel found them a tunnel with no problem. In fact, Frank had a sneaking suspicion she didn’t just find tunnels. It was as though tunnels manufactured themselves to suit her needs. Passages that had been filled in years ago suddenly unfilled, changing direction to lead Hazel where she wanted to go. They crept along by the light of Percy’s glowing sword,

Riptide. Above, they heard the sounds of battle—kids shout ing, Hannibal the elephant bellowing with glee, scorpion bolts exploding, and water cannons firing. The tunnel shook. Dirt rained down on them.

Frank slipped his hand inside his armor. The piece of wood was still safe and secure in his coat pocket, though one good shot from a scorpion might set his lifeline on fire.…

Bad Frank, he chided himself. Fire is the “F-word.” Don’t think about it.

“There’s an opening just ahead,” Hazel announced. “We’ll come up ten feet from the east wall.”

“How can you tell?” Percy asked.

“I don’t know,” she said. “But I’m sure.”

“Could we tunnel straight under the wall?” Frank wondered.

“No,” Hazel said. “The engineers were smart. They built the walls on old foundations that go down to bedrock. And don’t ask how I know. I just do.”

Frank stumbled over something and cursed. Percy brought this sword around for more light. The thing Frank had tripped on was gleaming silver.

He crouched down.

“Don’t touch it!” Hazel said.

Frank’s hand stopped a few inches from the chunk of metal. It looked like a giant Hershey’s Kiss, about the size of his fist.

“It’s massive,” he said. “Silver?”

“Platinum.” Hazel sounded scared out of her wits. “It’ll go away in a second. Please don’t touch it. It’s dangerous.”

Frank didn’t understand how a lump of metal could be dangerous, but he took Hazel seriously. As they watched, the chunk of platinum sank into the ground.

He stared at Hazel. “How did you know?”

In the light of Percy’s sword, Hazel looked as ghostly as a Lar. “I’ll explain later,” she promised.

Another explosion rocked the tunnel, and they forged ahead.

They popped out of a hole just where Hazel had predicted. In front of them, the fort’s east wall loomed. Off to their left, Frank could see the main line of the Fifth Cohort advancing in turtle formation, shields forming a shell over their heads and sides. They were trying to reach the main gates, but the defenders above pelted them with rocks and shot flaming bolts from the scorpions, blasting craters around their feet. A water cannon discharged with a jaw-rattling THRUM, and a jet of liquid carved a trench in the dirt right in front of the cohort.

Percy whistled. “That’s a lot of pressure, all right.”

The Third and Fourth Cohorts weren’t even advancing. They stood back and laughed, watching their “allies” get beat up. The defenders clustered on the wall above the gates, yelling insults at the tortoise formation as it staggered back and forth. War games had deteriorated into “beat up the Fifth.”

Frank’s vision went red with anger.

“Let’s shake things up.” He reached in his quiver and pulled out an arrow heavier than the rest. The iron tip was shaped like the nose cone of a rocket. An ultra thin gold rope trailed from the fletching. Shooting it accurately up the wall would take more force and skill than most archers could manage, but Frank had strong arms and good aim.

Maybe Apollo is watching, he thought hopefully.

“What does that do?” Percy asked. “Grappling hook?”

“It’s called a hydra arrow,” Frank said. “Can you knock out the water cannons?”

A defender appeared on the wall above them. “Hey!” he shouted to his buddies. “Check it out! More victims!”

“Percy,” Frank said, “now would be good.”