In Robert Brill’s splendid fairground set, the first thing that comes into view above a steel-pier scaffolding is a neon sign flashing “shoot! win!” Only four of the nine would-be Presidential assassins whom the show throws together actually got their man; the others form a sort of demented gang who just can’t shoot straight. Nonetheless, the homicidal itch in all of them was inspired by what Thorstein Veblen called “invidious comparison”—that particularly American brand of envy which agitates citizens to achieve and acquire, and perversely propels the deranged to spoil or to steal the power they conspicuously lack. “If you can’t do what you want to,” Sondheim’s gang sings, “you do the things you can.”

“Murder is negative creation,” Auden said. For this musical’s marginalized souls, taking aim at a President is the magical solution that can impose coherence on a wrecked life. In the first song, the straw-hatted fun-house proprietor (the excellent Marc Kudisch), who hands out guns to the malefactors as he introduces them to us, portrays them all as frustrated American dreamers: “No job? Cupboard bare? / One room, no one there? / Hey, pal, don’t despair— / You wanna shoot a President?” The assassins all have grandiose plans to claim, if not maim, the public imagination. “I have given up my life for one act, you understand,” John Wilkes Booth (Michael Cerveris) says to his accomplice. Booth feels betrayed by history and by the violence of the Civil War. Abandoned by destiny, he becomes it; he kills in order to heal. In his apocalyptic act, he controls history, death, even his own immortality. Later, in a debate with Lee Harvey Oswald (Neil Patrick Harris), Booth expounds on the idea of infamy. “They’ll hate you with a passion,” he says. “Imagine people having passionate feelings about Lee Harvey Oswald.” Likewise, Sam Byck (Mario Cantone), who is hellbent on flying a plane into the White House to kill Nixon—and who, incidentally, is dressed as Santa Claus—sees his act as holy and purifying. “You know the world’s a vicious, stinking pit of emptiness and pain,” he says on a tape that he makes to send to Leonard Bernstein. “I’m gonna change things.” (Byck was shot dead before he could accomplish his plan, but not before he’d killed two people.)

In the case of John Hinckley (Alexander Gemignani), who shot Ronald Reagan to win favor with Jodie Foster, history provides better lines than Weidman and Sondheim’s caricature. Hinckley understood that prestige is awarded on evidence; he also understood that in the aristocracy of American success there are no strangers. Shooting Reagan made him Foster’s equal in celebrity—an equality that, in Hinckley’s eyes, could make intimacy possible. Although Weidman has Hinckley referring to the shooting as a “historic act,” he misses the more piquant point that for the real Hinckley the assassination was a first step into show business. The shooting, Hinckley told his psychiatrists, was “a movie starring me,” with Reagan as co-star and “a cast of doctors, lawyers, and hangers-on.”

Only in the cakewalk to the gallows of President Garfield’s killer, Charles Guiteau (the compelling Denis O’Hare), does “Assassins” intimate the bright and deadly righteousness of the terrorist’s mentality. “I was just acting / For Someone up there. / The Lord’s my employer / And now he’s my lawyer, / So do what you dare,” Guiteau sings, in the song that best shows off Sondheim’s dramatic expertise.

Although Sondheim began his career, in the late fifties, peddling optimism (“Something’s coming, something good / If I can wait”), by the seventies he was selling the new pessimism: “Every day a little death . . . / Every day a little sting / In the heart and in the head.” To sing about the dark heart, instead of the big heart, became his musical mission, a newfound nihilism that proved to be a mother lode. From the poisoned well of hate, revenge, envy, and disappointment, Sondheim drew the pure water of lyric feeling. His musicals abound with emotional terrorists (the overbearing Momma Rose, in “Gypsy”; the hysterical Fosca, in “Passion”) and with killings (“Pacific Overtures”; “Into the Woods”). His masterpiece, “Sweeney Todd,” tells the story of a serial killer. Sondheim spoke to the disenchantment of the times, and his approach turned him not so much into a celebrity as a theology. “Is Stephen Sondheim God?” New York asked in one headline. That’s sort of how the young playwright Charles Gilbert felt—he’d written a script called “Assassins”—when Sondheim contacted him about using his idea. “I was pretty cheeky—I offered to work on it with him—it was like writing a letter to God,” Gilbert told Sondheim’s biographer Meryle Secrest. To a man of Sondheim’s ambition and sourness, the doleful, contrarian subject matter was irresistible.

This dark cartoon—a kind of glib carnival of carnage—was first performed in 1991, at the beginning of the Gulf War. It was meant to have its Broadway début just after September 11, 2001. The delay of more than two years has not helped the show’s karma or its message. The musical views terrorism as the random acts of individual madmen, not as the coördinated civil mayhem we now know. In its heavy-handed exposition, the show reminds us that “every now and then / A madman’s / Bound to come along. / Doesn’t stop the story— . . . / Doesn’t change the song.” Well, yes, it does. The jihadists of September 11th imprinted their sense of death irrevocably on this nation. In one way or another, we are all now survivors. “Assassins”’s portrait of American invincibility has come to feel almost as Pollyannaish as the traditional musicals against which Sondheim’s work rebels. In a new song, “Something Just Broke,” Sondheim acknowledges the survivor’s psychic numbness—“Something just spoke / Something I wish I hadn’t heard / Something bewildering occurred”—but he’s unable to move from generalization to penetration. In light of our new hell, the violence that “Assassins” addresses seems antique, quaint, almost sweet: Terrorism Lite.

Although “Assassins” may not think deeply, it does at least think out of the box, which is itself an achievement. It is well sung, gorgeous to look at, and meticulous in its detail. Still, it has been freighted with more weight than it can properly carry. It promises a journey into the psychopathic interior, but it remains resolutely on the outskirts. “The show will live on,” André Bishop wrote in his introduction to the 1991 version. I respectfully beg to differ. Despite the boldness of its surface, “Assassins” is more semaphore than metaphor.