Bathed in dim candlelight, 50 opera lovers waited silently before her in a cafe in Colonia Libertad, a banged-up neighborhood famous for boxers, smugglers and gangs that slouches into the steel wall separating Mexico from the United States.
She opened her palms and began "Pur Dicesti, O Bocca Bella" ("Beautiful Mouth, at Last You Have Spoken").
Outside, a motorcycle growled by; a car alarm babbled in reply.
Never has opera seemed more welcome and more appropriate for Tijuana than these days, when city streets have run with blood and vengeance.
One of Tijuana's leading sopranos, Martinez was here to offer her antidote, a caress to the sweeter part of her city that the world rarely notices.
Like resisters to some totalitarian regime, her audience huddled in the small space. They were teachers, office workers and merchants from Tijuana's middle class -- one of the largest of any city in Mexico -- who have wanted more for their children than the strip clubs and velvet painting the city is known for.
They sat attentively, some hunched as if in prayer for a little more than an hour, listening to Neapolitan love songs, to Verdi, to Puccini and to the plaintive bolero "Besame Mucho": "Kiss me, kiss me a lot, as if tonight were the last night . . . because I fear to lose you, to lose you again."
A medieval violence has overwhelmed this ragged but normally optimistic border town. Two factions of a drug cartel fight daily for street primacy, leaving a trail of shootouts, decapitations and kidnappings. In January, police arrested a man known as "El Pozolero" ("The Soup Maker"), who allegedly admitted to dissolving about 300 bodies in lye over the years, paid by a drug kingpin, "El Teo," who has stalked people's nightmares for months.
From their streets of madness, Tijuanans have sought refuge indoors.
"The only good thing is that these kinds of cultural events have grown like never before, perhaps because people are looking for some kind of harmony," said Suzy Fuentes, whose brother, Enrique, opened the Cafe de la Opera, where Martinez performed.
Tijuana's love affair with opera and classical music began in 1991. An 18-member professional Russian chamber orchestra left the remains of the Soviet Union and moved to Tijuana at the behest of a local music promoter.
In a town that had mostly valued music by how well it backed the gyrations of strippers or matadors, the Russians implanted classical music instruction and bel canto technique, and opened Tijuana's first music conservatory.
They spoke little Spanish and the children spoke no Russian. They used signs and kept to the language they had in common: music. Most of the Russians have left for San Diego, Los Angeles or elsewhere. But they stayed long enough to foster a generation of young musicians and singers.
Many of their students, like Martinez, honed their talents in the Cafe de la Opera.
In 2002, Enrique Fuentes, an opera fanatic and San Diego teacher's aide, opened the cafe with thrift store furniture and his own savings, modeling it after the salons in Vienna and Milan, Italy, where fans gather for coffee, pastries and the serenades of opera singers.
"This place, in the middle of the Libertad, you wouldn't expect it," said Laura Fernandez, a homemaker and a resident of the neighborhood for many years, as she sat waiting for Martinez to begin.
In 2005, Fuentes organized the first Opera in the Street Festival in front of his cafe on 5th Street, a couple of hundred yards from the steel wall. It attracts thousands of people every July and has become one of the city's most important cultural events, put on largely without government help.
Fuentes closed the cafe in 2007, but still holds occasional events there. He and the landlord, a construction worker named Eugenio Romero, keep it appointed, ready for the moment when Tijuana might support their strange idea a little more. Until that happens, a dancer teaches salsa there each Friday night.