VIDEO: 'Chicago Fire' cast dishes on what's in store for season two, premiering Tuesday

“Chicago Fire” is one of the few success stories to emerge from NBC’s freshman class last fall.

With an average of 8.1 million viewers when DVR playback is factored in (and faring especially well with folks in Chicago, where it’s filmed), the Dick Wolf-produced drama (“Law & Order”) built its audience and found its legs during season one.

The Peacock net duly rewarded it with a spin-off, “Chicago PD,” coming later this season and switched it to a new night in hopes of igniting an even bigger fan base.

The series, co-created by Derek Haas and Michael Brandt (“3:10 to Yuma”), moves to its new slot this week at 9 p.m. Tuesdays, following a sweet launching pad with NBC’s hit singing competition, “The Voice.”

Fans will see some new faces at Firehouse 51 in the season premiere.

Government number cruncher Gail McLeod, played by Michelle Forbes who did a memorable turn as Rosie Larsen’s mother in “The Killing,” has been assigned to make the department do more with less. That means firehouses around the city have been closed down, which leaves the tight-knit crew at 51 having to absorb a couple of new guys: Lt. Sullivan (veteran Chicago stage actor John Hoogenakker) and rescue squad member Jeff Clark (Jeff Hephner). Both Hoogenakker and Hephner were in Starz political drama “Boss,” shot in the same West Side studio, Cinespace Chicago, as “Chicago Fire.”

Hephner describes his character as “a bit mysterious, a bit quiet. Has a military background,” he said. “There’s a few things that happen that call his loyalty into question.”

Downsizing and budget cuts aren’t the only threats facing the firehouse in the season premiere.

“We’re dealing with a serial arsonist who seems to be targeting certain members of the house,” said Jesse Spencer, who plays Lt. Matthew Casey. Casey is coming off a rough first season that resulted in the murder of his fiancé.

“He’s really tried to move on from that,” Spencer said. “He’s been on vacation for about a month. He can’t wait to get back into work.”

He also finds himself taking on a pseudo-parental role with a close friend’s children.

“He sort of becomes the surrogate father and has to look after these kids,” Spencer said. “That’s sort of part of the healing process for him coming out of season one.”

More baby drama is in store for Lt. Kelly Severide (Taylor Kinney), whose ex-girlfriend bounced back on the scene sporting a baby bump in the season finale.

Rookie Peter Mills (Charlie Barnett) ended the season contemplating a career change.

“He’s not really sure where he is in life,” said Barnett, whose character is toying with the idea of becoming a cop. “Everything is kind of shattered and he’s trying to pick up the pieces.”

By “everything,” Mills means his career and his love life. His relationship with paramedic Gabriela Dawson (Monica Raymund) went up in flames, largely because Dawson still carries a torch for Casey.

“We’ll definitely see her have maybe one or two loves coming in and out,” Raymund said. “Maybe one crush and then something else that might be a little more serious.”

The actress wants more than her personal life to heat up this season.

“I really want to see my character do more action,” she said. “I would love to keep running into fires and play with the boys.”

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