Underdogs by Robert Ryan

A pulse-pounding thrill ride from the tunnels of Vietnam to a secret world underneath the sidewalks of Seattle
Seattle burned to the ground in 1889 and a new city was built on top of the old. A century later, the original Seattle remains: empty streets, crumbling sidewalks, and pitch-black passageways, twelve feet beneath the modern metropolis.
When a stickup goes horribly wrong, Hilton "Rabbit" Babcock and his eight-year-old hostage, Ali, tumble through the rotten floor of an abandoned warehouse and into the subterranean city. They are not alone. Strange, desperate characters lurk in the shadows of old Seattle, and they don't take kindly to visitors. But with the cops and the ruthless drug queen he's in debt to waiting aboveground, Rabbit has little choice but to plunge deeper into the dark, dragging Ali along with him. To bring her out, the Seattle PD turns to a Vietnam vet who spent his war years flushing the Viet Cong from their jungle tunnels. Is Lewis ready to face his demons and go underground again? Ali's life might just depend on it.