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To kick off its celebratory 30th season, Signature Theatre down in Arlington is returning once again — for the 30th time, in fact — to its own signature: Sondheim. But even for the regional theatre that performs his work more than any other, you might be surprised at the skill and ardor brought to the new production of Assassins, going on now until September 29.

In a vaudeville-style, generally plot-free examination, the four men who succeeded — and several of the people who tried and failed — at murdering U.S. presidents, steel their resolve, secure their weapons, and plead their cases. As directed by Signature artistic director Eric Schaeffer with a book by John Weidman, Assassins casts a probing, discerning eye toward history, and I do recommend letting it show you what it finds.

Here’s John Wilkes Booth (Vincent Kempski disappears into the role completely), holed up in a Maryland barn with a broken leg, trying to argue that Lincoln was the one tearing the country apart. Here’s Sara Jane Moore (Tracy Lynn Olivera is so real you feel like you know her in real life), practicing her aim on a bucket of KFC chicken before turning the gun on Gerald Ford. And here’s Giuseppe Zangara (Ian McEuen refuses to let the furious broken English devolve into one-note), so wracked with pain and frustration he barely cares who he tries to shoot — it might as well be FDR.

I thought Signature’s most recent dip into the Sondheim well, last year’s Passion, was a top-tier production of one of his second-tier musicals. But this time, the cast and crew are so good they truly elevate the work. Kathleen Geldard nails the costumes, from the 1860s to the 1980s, and Chris Lee’s lighting is a trip, helping the mood shuffle from hilarious to heartbreaking and back again.

Obviously, the characters are a dark and misguided bunch, with more than a thin vein of crazy running through them. But what caught me off guard was how sad they all are, and even more so together.

Charles Guiteau (Bobby Smith lets the delusion run deep) may have been the 19th century’s biggest loser; he failed at everything he ever tried … except for slaying James A. Garfield. Samuel Byck (Christopher Bloch, spitting rage) is so lonely and angry he doesn’t even bother to take off the Santa suit. He could practically be considered a forefather of the incel movement, which goes double for Evan Casey’s wounded, pathetic John Hinkley. Not only does Hinkley fail to kill Reagan, he can’t even stop the Gipper’s wisecracks. Rachel Zampelli’s Squeaky Fromme will make you forget all about Dakota Fanning in Once Upon a Time in Hollywood; Zampelli brings far more pep to the role. Most touching of all is Lawrence Redmond’s Leon Czolgosz, the man who assassinated McKinley. Redmond plays him as a lost soul of the working class, twisting ideas about social justice into desperate violence.

The songs are even “less hummable” than usual, but you won’t notice when Casey are Zampelli are crushing “Unworthy of Your Love,” with dreams of Jodie Foster and Charlie Manson in their eyes. Or during “The Gun Song,” a showstopper that goes off (sorry) without a hitch.

Oh what the heck, let’s double-down on the gun puns: This show shoots to kill. And it does not miss.

Assassins is at Signature Theatre through September 29th.