This graph is a spoiler: The novice viewer of “Tosca” was blown away. She never imagined that the blasphemously lustful Baron Scarpia (American bass Greer Grimsley), head of Rome’s secret police, would die at the end of Act II, stabbed to death by the title character, opera singer Floria Tosca (French soprano Sylvie Valayre). The first-timer likely didn’t know that Tosca’s lover, the politically active artist Mario Cavaradossi (American tenor Marcus Haddock), would die at the end of the opera, victim of real bullets fired in what Scarpia promised would be a mock execution. And imagine not knowing that Tosca would leap from the parapet of Castel Sant’Angelo in the final scene. Imagine, too, hearing this 1900 opera by Giacomo Puccini, seeing it performed on Jean-Pierre Ponnelle’s expansively lofty set, hearing a bevy of beautiful arias — all for the first time: being astonished by the plot and in thrall to fine singers from around the world, all exceptional actors. It must be a thrilling experience, far removed from the jaded operagoer heard muttering “just another ‘Tosca’” over a pre-performance supper prior to curtain of San Diego Opera’s 44th season. San Diego Opera has produced “Tosca” seven times if one counts this season, in which there were/are a total of five performances through Feb. 4. The current “Tosca”—stunningly accompanied by San Diego Symphony (oh, that brass section), conducted by Edoardo Muller, staged by Andrew Sinclair and costumed by Suzanne Mess—is a humdinger in a world of shrinking resources. In a rare curtain speech, artistic/general director Ian Campbell talked of losing $3.7 million in endowment funds due to the market downturn; of other opera companies now shuttered; of his canceling of one production next season; of cutting the number of performances until the situation improves. Campbell pleaded for funds, attendance and special gifts. Grimsley, known to Facebookers as “an opera god,” is the quintessential serpent-like Scarpia, whose body suggests much darker visions than we are allowed to glimpse. Vocally, he is a wonder—a large, far-forward, yet sonorous voice unlimited in range and color. When he takes off his jacket and vest in preparation for lovemaking every woman gasps internally. Valayre and Haddock have something in common, lower- and mid-register voices that have no breaks in quality from the high ranges. The vocal production of each is seamless with no shifts in what are called the “transport tones.” In other words, all parts of the voice lie in the same pipe. For one used to color changes in each of a singer’s three “voices,” this is a revelation. Each is a marvelous singer, rich in quality yet unhampered in the top ranges. The diminutive Valayre, a lovely figure in her period gowns, is a dynamo, a spitfire, dramatic Tosca with plenty of humor, joie de vivre and petulance. She’s a joy to watch, and to hear, especially when she nails a high pianissimo or sings a usually broken phrase in “Vissi d’Arte” all in one breath with plenty of room to spare! Exceptionally handsome and dramatically engaging, Haddock has a baritone quality that soars surprisingly and easily to the requisite vocal heights. In combination, he and Valayre are quite extraordinary, unlike any other pairing heard in all these years of opera-going. To the novice it may seem like business as usual; it’s a super production for one’s first experience of the work. Remaining performances of “Tosca” are 8 p.m. Friday, Jan. 30; 2 p.m. Sunday, Feb. 1; and 7 p.m. Wednesday, Feb. 4 at the Civic Theatre, 202 C St., San Diego. For tickets (from $36), visit www.sdopera.com or call (619) 533-7000.