Early in the morning, Maria and her comrades-in-arms creep out from the storm drains under the Caracas streets.
They put on their helmets and black masks and take up their wooden shields.
"The ruckus is starting," Maria, 30, tells her companions. And off they go to look for the riot cops.
Venezuela's political opposition insists that demonstrations must be peaceful if they are to achieve political change in a country wracked by hunger and violence.
But unlike some, these young people are not willing to march patiently to express their frustration with the government.
"The adrenaline drives us against them," says one of the group, Alejandro, 19. "Every day it gets harder. But we are ready to do anything."
The authorities call them "guarimberos" -- rioters -- and even "terrorists."
They call themselves "the resistance" against President Nicolas Maduro and his allies in the leftist "chavista" movement inspired by late president Hugo Chavez.
One of the leaders of the Altamira group, Julio, 28, says he used to be a mechanic.
"How did I become a guarimbero? Out of hatred," he says.
"If I got hold of a chavista now, I would burn him right here."
They barricade the streets and when the military police fire tear gas, they hurl back rocks and Molotov cocktails.
Behind Maria, out climbs Manuel, an 18-year-old who has a two-year-old daughter.
He shows a scar on his hand where a tear gas canister hit him.
"I won't stop fighting until the government goes," he says.
Prosecutors say 57 people have been killed in the unrest since April 1, many of them shot dead in the chaos of the protests.
Among the regular angry protesters and the looters, gunmen on motorbikes have struck, the state prosecution service says.
Last weekend, a 21-year-old man was set on fire at an opposition protest. Maduro said it was because he was a government supporter. The opposition said the man was lynched for thieving.
The government blames the "guarimberos" for such violence. But the opposition accuses the authorities of sending armed thugs to the protests.
In the chaos, it is easy for government agitators "to infiltrate" the demonstrations, says Colette Capriles, a sociologist at Simon Bolivar University.
In Venezuela's crisis, the street warrior groups bring together various strands beyond the fringes of politics.
"These kids are hard to categorize," says Colette Capriles.
"There are groups of warriors. There are some who think they are in a video game. There are some who are totally mentally deficient," she adds.
"It is tragic because they put lives at risk. But one thing should be made clear: they are not part of the political opposition."
Much international attention has focused on the mainstream center-right and its chances of prevailing over Maduro.
For Julio, politics doesn't even come into it. If rioting makes it easy for the government to demonize the opposition, he does not care.
"We have nothing to do with the opposition, and they do not like us either," he says.
Maria's group shelters at night in the deep culverts and emerges at dawn among the flower beds of Altamira Square -- the heart of one of Caracas's poshest, and most pro-opposition, districts.
Most of them do not live around here, but local residents give them food and drink -- even the occasional shower or bed for the night.
At night, they climb back down into the drain to hide.
"The fear is always there," Maria says, tapping her heart.
"It is what drives you on. We will keep on like this until the dictatorship falls."