No hitting my friends!” Tyson charged in, putting himself between the Hydra and Annabeth.
As Annabeth got to her feet, Tyson started smashing at the monster heads with his fists so fast it reminded me of the whack-a-mole game at the arcade. But even Tyson couldn’t fend off the Hydra forever.
We kept inching backward, dodging acid splashes and deflecting snapping heads without cutting them off, but I knew we were only postponing our deaths. Eventually, we would make a mistake and the thing would kill us.
Then I heard a strange sound—a chug-chug-chug that at first I thought was my heartbeat. It was so powerful it made the riverbank shake.
“What’s that noise?” Annabeth shouted, keeping her eyes on the Hydra.
“Steam engine,” Tyson said.
”What?” I ducked as the Hydra spat acid over my hea
