EXPOSED and vulnerable. These aren't words that you'd usually hear from MediaCorp artiste Rui En. She has often projected an unflappable and icy-cool demeanour, both on- and off-camera.

But filming high-octane cop drama Unriddle II left the 31-year-old emotionally wrought - even till today, two months after the show wrapped its shoot.

"I've been acting for a while, but this is the first time I have no idea how my scenes will actually turn out on television," she told The New Paper at the press conference for the show last Tuesday.

"Just thinking about it, it's nerve-racking. It's like being in a relationship where you give a lot, and vulnerability is all you can feel."

The 20-episode series, a sequel to 2010's popular Unriddle, premiered on Channel 8 at 9pm on Monday.

It reunites original cast members Rui En, Chen Liping and Tay Ping Hui as elite members of the Criminal Investigation Department.

New additions include Elvin Ng as Rui En's competitive teammate and Rebecca Lim as a mysterious psychiatrist.

Replete with twists and turns, Unriddle II sees the tanned, lean Rui En delving into darker and more hard-hitting territory.

Viewers who have caught the trailer on YouTube would have noticed the changes in her character, Xiaoman.

In one scene, she stumbles around, dazed and bleary-eyed, while in another, she points a gun at herself.

"We had several scenes that were really sad and emotionally draining," Rui En recalled, declining to provide more details as it might give the plot away.

"When it comes to acting, I've always been very particular about timing and control; I tend to hold back so that I don't overact...

"But for this one, I felt I just had to let loose. It got to the extent that I started cursing a lot on set (like dropping the F-bomb), which shocked my co-stars and the crew. They certainly didn't see that coming."

Aside from spouting profanities, Rui En revealed that during the initial stages of filming, the sheer intensity of the scenes made her feel so "low and depressed" that she felt "suicidal" at one point.

"The thought did cross my mind," she said. "If I hadn't snapped out of it, I figure I would have gone crazy."

Thanks to co-star Chen, she eventually managed to purge the negativity. "I had a chat with her and she told me, 'You just have to let it go.' I'm very thankful for that," said Rui En.

"Of course, her laughter also helped... Liping tends to burst into laughter after every serious, emotional scene - I have no idea why, but it's infectious and makes me laugh along."

The 46-year-old veteran actress and mother of one told The New Paper in a separate interview she became concerned that Rui En was not stepping out of her character even after the directors had shouted "cut".

'I was worried for her'

"Those two nights that we filmed the finale, I was worried for her... She told me she felt very negative, which was something I could understand as I felt that same way too at one point during filming.

"I told her she had to let the character go for a while."

Though she was emotionally prepared for the heavy plot, Chen said that she, too, got depressed during filming. But she doesn't want to let on how much it affected her, only that she spoke less at home and became more pessimistic.

Added Chen: "It's hard to make a clean break.

"If we get out of our roles (completely), we would have to spend time getting into it again. The pace of filming is very fast; we don't have time to build up our emotions."

Chen recounted the day she, Rui En and Tay filmed from 8am to midnight.

The scenes involved Tay's character, Zhang Yuze, becoming wheelchair-bound and later falling to his death - which Tay readily revealed at the press conference.

Rui En and Chen had tedious crying scenes from day to night.

"We were already feeling emotional from reading the script. In order to wrap up filming faster, we held on to these emotions so we could feel the sadness on set," said Chen.

But she's adamant that she doesn't take her work home.

Her husband, actor Rayson Tan, had given her that piece of advice around a decade ago, when she got affected by her famous role Mo Wanwan in the long-running Channel 8 drama Holland V and became quick-tempered at home.

She's also hesitant about letting her son, 10-year-old Zavier, watch Unriddle II - even though he's a big fan.

Said Chen: "Boys like police, guns and action. He even told me not to change the hairstyle I had in Unriddle II.

"He doesn't like my new hairstyle in Joys Of Life (the Channel 8 drama I'm currently filming) because it's very 'aunty'."

This article was first published in The New Paper.