To find out the real history of Tucson you have to go underground. Down into the two-street underpasses that connect the university neighborhoods with downtown. Dank, dark, spotted with puddles of urine, they are places where drug deals go down and drunks take siestas. With its twirled Moorish columns and ogee arches, one underpass even has pretensions toward being art. The one thing these short, concrete labyrinths have in common is the intricate layers of graffiti that cover their walls. To the majority of Tucsonans who rumble through in their cars, the eons' worth of spray paint are just a blur. But to those brave enough to walk through, the words and drawings are like gazing into madness, and reading the desperate pleas of street hieroglyphics. Every so often, the city attempts to scrape the walls clean. But that only opens more space for the angry and the artistic, and before long the walls again are covered with scribbling. Abstruse gang code words, innumerable human profiles and the tried-and-true formulae of graffiti like "Fred's Rule," and "For a good time call . . . " fill up most of the space.

But scattered along these 60-foot- long walls are some of Tucson's more basic truths. "Punk Is Dead," scrawled in basic black, screams from a wall near one tunnel's middle. Farther down, "Hitler Was an Artist" is splashed in red with big loopy swastikas for accents. "There Is No Room in This World for Hate" is spelled out in small, obsessively neat letters. Malcolm X's profile in black stares above the word "Queen." One of the biggest symbols of all, though, is the word "Rainer," spelled out in bright green paint by a steady hand. Here among all the raw emotions, secrets and dirty words is the unlikely name of a blues musician. Of all the compliments he's received, making it onto the walls of the Fourth Avenue tunnel is the surest sign that Rainer's hit the big time.

Rainer Ptacek is a bluesman. A white bluesman. A musician with the kind of talent that comes along once in a lifetime and rarely in Tucson. Rainer (pronounced RYE-ner pa-TAH-chek; he never uses his last name) is both a powerful solo performer and an engaging frontman with his blues/funk trio, Das Combo. Possessing a voice that is good enough to get by, but a mean way with a slide guitar, Rainer also is one of the best steel-bodied guitar players around. He is every bit as talented as most of the so-called "national" blues acts. But Rainer doesn't have a record deal. He doesn't tour, either. Until now, Rainer--Tucson's most respected musical homeboy--has refused to get involved in the music business. In fact, about the only place to catch him is with Das Combo at its regular Saturday-night gig at Cushing Street Bar. Next week, he will make a rare Valley appearance, playing solo at the Rhythm Room.

All along, Rainer's been happy raising a family, working a dream job and being a large musical fish in a small pond. But all that may be changing. These days, Rainer's thoughts have turned to buying a house, landing a record deal and "getting my stuff out there."

Rainer works, in the loosest sense of the word, as a guitar tech at the Chicago Music Store. A scene that even Dickens couldn't have imagined, the Chicago Music Store in downtown Tucson is a monument to the pack-rat impulse, a funky menagerie of anything musical. The owners buy, sell and trade everything from guitar picks to drumsticks, from sheet music to PA systems, from bell mutes to sousaphones. Housed in Tucson's old JC Penney, the Chicago Music Store runs on the never-take-inventory, never-ever-clean-up theory of retail. For customers, though, some of whom come from as far away as India, that translates to: If the Chicago Music Store doesn't have it, it don't exist. Upstairs, under a huge, vaulted glass skylight, are rooms where brass instruments are stacked into piles 20 feet high. On the main floor--the site of Jodie Foster's guitar- string-stealing scene in the film Alice Doesn't Live Here Anymore--guitars are propped up in ragged lines and telephones ring off the hook. Downstairs is Rainer's lair--a bowling-alley-size room filled with every member of the guitar family. Electric guitar bodies with names like Fender Bullet, Memphis Bass and Hopf Special lie in dusty heaps all around. Stringless mandolins and banjos hang from overstuffed shelves that line the walls. Here and there a random bare bulb shines out. A coat of dust covers everything. Forgotten treasures surely abound. A stack of multicolored Flying Vs peek out from the bottom of one pile. An intricate inlaid wood acoustic guitar hangs in an obscure corner.

In the middle of this scene--like the final shot of Citizen Kane, in which the camera pans back to reveal Kane's endless plunder--is Rainer's workbench. Photographs of his wife and sons are at eye level. Cassettes of music by Verdi, Frank Stokes and Ma Rainey are piled up on an overhead shelf. A biography of Wittgenstein and a book titled The Signifying Monkey: A Theory of African/American Literary Criticism lie nearby. Dressed in jeans, tee shirt, black leather vest, black boots and a Cleveland Indians baseball cap, Rainer drags on a cigarette while cleaning and restringing a Black Fender Squire II Stratocaster. In a sign of the times, this version of America's legendary guitar has "Made in Korea" stamped prominently on the neck.