He whistled as loud as he could—a good New York cab whistle that would’ve been heard all the way from Times Square to Central Park.
Shadows rippled in the trees. A huge black shape bounded out of nowhere—a mastiff the size of an SUV, with a Cyclops and a harpy on her back.
“Hellhound!” Frank scrambled backward.
“It’s okay!” Percy grinned. “These are friends.”

The Son of Neptune, Chapter IL