Learn why Law & Order actor Hugh Dancy had an “out of body feeling” while filming on the SVU set and with actors Mariska Hargitay and Peter Scanavino.

Mariska Hargitay, who has starred on Law & Order: Special Victims Unit for decades, is a bit of an on-screen legend — even among fellow actors in the franchise.

For an astonishing 26 seasons, Hargitay has embodied the role of Olivia Benson on the NBC crime drama, earning the seasoned investigator the distinction of being the longest-running prime-time live-action character of all time.

But according to one Law & Order star — who shares scenes with her in the two-part “Play with Fire” crossover event — Hargitay hasn’t let the unprecedented success go to her head or weaken her commitment to the job.

Hugh Dancy, who plays Executive Assistant District Attorney Nolan Price on Law & Order, spoke to NBC Insider earlier this week about his time on set with Hargitay and other SVU stars, some of whom he worked with for the time, as part of the action-packed crossover.

“I’m a little bit in awe of the degree to which she self-generates her energy and enthusiasm,” Dancy told NBC Insider of the experience of filming alongside her.

The crossover blends the worlds of both Law & Order and SVU as New York City’s finest investigators and prosecutors come together to track down an elusive serial killer on the loose.

It’s a mission that takes all hands on deck as the killer continues to slip from their grasp, giving the crime fighters from both the NYPD’s homicide division and special victims unit plenty of opportunities to work side by side.

Why Hugh Dancy found Mariska Hargitay “Impressive”

While Dancy said he was “more than aware” of Hargitay’s history-making run and legacy on SVU before filming the crossover, he found it  “impressive” that she still found so much joy in her job.

“It’s deceptive because you don’t show up and think here’s a person who’s done… 26 years of a show, you feel like, here’s a person who just seems to be excited to get into the day’s work,” he said. “It’s very impressive to me.”

Filming on the set of SVU also meant that Dancy got to step into the courtroom that was once used for Law & Order when the flagship show began in 1990. Today, it serves as the courtroom for SVU cases.

“That’s gotta be the longest, consistently used television set anywhere in the world, I would think,” he said.

Hargitay wasn’t the only actor from the SVU universe to cross paths with Dancy in the crossover. Dancy also shared scenes, for the first time, with Peter Scanavino, who plays his SVU counterpart ADA Dominick Carisi Jr.

“Peter is a great guy,” Dancy said of working together. “It’s all very familiar of course, in the best way, and I think, hopefully, that’s what comes across in the episode is that… we have a shared agenda and a shared understanding of how best to get there.”

Hugh Dancy describes “out of body” feeling on SVU set

For Dancy, the “fun” of the crossovers is that he gets to be more immersed in the Law & Order universe, beyond the show he normally works on.

“Obviously, Dick Wolf invented this multi-verse idea almost, but most of the time we’re not in it,” he said. “I’m in our law offices and our courtroom and then you go and visit their set and you say, ‘Oh wait, it feels like there really are other people on the other side of the city who are doing the same thing as us.’”

Dancy admitted that the experience of walking onto a different set, while still personifying Price’s character and stepping into a “deeply familiar” courtroom was a bit surreal.

“It’s a kind of out of body feeling,” he explained. “Part of it is like, ‘Wait… I’m doing a different job. I’m visiting somebody else’s set, but I’m playing the same character, I’m wearing the same suit, but nobody here knows me.”

Although each show’s cast and crew has their own set of inside jokes and way of doing things, Dancy said it didn’t take long for the casts to feel united.

“I think the last day of filming was like me, Tony (Goldwyn), Mariska, Maura (Tierney) and Ice T as well, briefly,” he said. “It felt like we were fully meshed at that point.”