Reliquary is the 1997 New York Times best-selling sequel to Relic, by American authors Douglas Preston and Lincoln Child.

The legacy of the blood-maddened Mbwun lives on in Reliquary, but the focus is shifted from the original museum setting to the tunnels beneath the streets of New York City.

The mystery soon leads underground to the Mole people, and even deeper towards enigmatic beings called the Wrinklers.

In the end, it is revealed that the Wrinklers are led by Frock, who has refined a modified version of the Mbwun plant, created by Kawakita to regain the use of his legs.

Lieutenant D’Agosta is with some divers searching for a brick of heroin that was tossed over a bridge into the Humboldt Kill, aka the Cloaca Maxima.

This is an area of the Harlem river where lots of human waste and other refuse piles up, making the water murky and disgusting.

A New York young man proposes to his girlfriend Tanya at Belvedere Castle, but when he goes into the Men’s room to urinate, something appears.

Pendergast, posing as a smelly homeless man, appears in the homicide office to visit with D’Agosta.

Mrs. Wisher, the wealthy socialite mother of a young woman who disappeared, makes a deal with Smithback for his exclusive coverage of her Take Back the City initiative.

Pendergast found some strange stuff, including a throne and hut built from human skulls, in the Astor tunnels.

Meanwhile, there’s a huge Take Back the City event going on in Central Park, which is probably going to hinder the police in their effort to roust the homeless.

Waxie and Duffy the engineer head down to manually turn off valves to stop water from entering the tunnels.

D’Agosta, Mephisto, and AP arm themselves from the FBI armory, and head into the tunnels to blow up the exits into the river.

As the group is fleeing, Margo used her Vitamin D bottles on the creatures, killing a bunch and driving the rest back.