Timing is key for a comedy actor finding her serious side

The latter was "a nightmare but very sweet," laughs Plaza. "It was a good birthday."

Plaza was in the capital in June for the Edinburgh International Film Festival premiere of Life After Beth, a zombie rom-com about a boy (Dane DeHaan) who loses his girl (Plaza) to the ranks of the undead. The film is the first feature of Jeff Baena, the I Heart Huckabees writer turned director who is also Plaza's partner.

While it is hardly the first off-screen partnership to become an on-screen one, Plaza admits that other people wondered if such 24/7 working would be good for any relationship. She had no doubts, however.

"I was the one who suggested it. I thought it was more important just to make a good movie. I had a feeling that we were just meant to work together, so I wanted to throw it at the wall and see if it stuck."

"He was really collaborative and we were both on the same page the whole time. It always felt like we were meant to be in those roles. It was really cool to see him do his first movie. Since I first met him I always thought he should be directing."

The two are graduates of New York University's Tisch School of the Arts, both studying film production. Plaza, too, has ambitions to be behind the camera one day. "I think I can be a natural leader, but I'm much more indecisive than he is, so I have to hone that skill."

Training in film production is not the usual route for an actor, but in a career that has stretched from the action comedies Scott Pilgrim vs The World and Safety Not Guaranteed to Monsters University, Plaza has found her degree adds to the on- set experience.

"Just having the experience of being on different sets is the best kind of preparation to be an actor, because you learn so much from the other side of things. When I was in film school I was assistant directing a lot of movies. It was a great experience for me to see the whole operation from behind the camera. You appreciate everyone's job. One quality of really successful actors I've met on different jobs is that they are really in sync with the production and the crew."

Plaza's craft has been honed at the Upright Citizens Brigade Theatre in New York, a comedy club founded in 1999 by her Parks and Recreation co-star, and mentor, Amy Poehler. Improvisation is competitive, she says, but it is about team work too.

"It's all about the timing. You could have something brilliant to say but you have to say it at the right time, and before someone else says it. But the thing about the Upright Citizens Brigade is that their mission is all about support, making your partner funnier than you, and in turn that makes you funny. It's a give and take."

Talk of the UCB and improv takes us back to 2009's Funny People, directed by Judd Apatow and starring Adam Sandler as a film star going back to his comedy roots in the clubs. Plaza played comedian Daisy Danby. To get the part, Plaza wrote a five-minute script and filmed herself performing it. Most stand-up comedy, unlike improv, cannot be done on the hoof. "You have to have your material down. You have to know what you are saying and how you are saying it."

Apatow gave her the part, then asked her to come to LA and start doing stand-up for real.

"I started writing what I thought was stand-up but I didn't know what I was doing. Looking back on it now I'm so embarrassed by the jokes I wrote at the time, but they were working for me then."

But even dying on one's posterior has its lessons, she reckons.

"It's good to fail in front of a lot of people. It makes you a better person or something," she laughs. It also makes you work harder.

"I feel like I need more of that in my life now. The more I work on TV and stuff, I'm losing that edge of live theatre. Amy Poehler is really good at keeping that going in her life and she always tells me you've got to go back to UCB and do a show, just fail, or look embarrassed, just something, so it grounds you."

Parks and Recreation, a mockumentary about a small-town parks department, is now in its seventh series in the US and can be seen here on BBC Four. Plaza plays the magnificently lugubrious one-time intern April Ludgate. If there is an office parade to be rained upon, April is usually the one with the hose.

"I never imagined I would be on a TV show, much more one that has gone on for seven years. It's been really great to have a steady job as an actor, which is rare. It's allowed me to have a window of time where I can do other things then go back to my 'home' there."

Poehler and Tina Fey - the creator of 30 Rock and Poehler's Golden Globes co-host - have been an inspiration, says Plaza.

"They've inspired an entire generation of girls, me included, that see two really smart, funny women just not caring what anyone thinks about them."

They have also shown the way in keeping close control on their careers. Fey has now made the move into films (Date Night, and the upcoming This is Where I Leave You), and Poehler is taking a similar path with They Came Together. That is another lesson for Plaza, who now lives in Los Angeles.

"The only control you have, really, is to say no to things and to stand your ground. There are so many things coming at you in Hollywood, opportunities and people wanting things from you. It's intoxicating and you just have to take a step back and think what do I really want to put out into the world."

It is particularly tricky, she says, when offers come with big dollar signs attached. But it's a mistake, she feels, to take something out of fear of never working again.

"That's the thing about being an actor. You never feel safe. You always feel 'I've got to get this next thing or who knows what is going to happen'."

She will soon be seen in the comedy Mortdecai with Johnny Depp, before appearing in two dramas: About Alex, and Ned Rifle. Drama is another change in direction, and one she admits to finding daunting.

"Doing comedy is easier for me because I can have a wall up. Most of my comedy comes from not letting people in on what I'm really thinking. I think that's why I'm drawn to do drama - I'm ready to emote."

Life After Beth opens in cinemas on October 1