What do you do when your loved one suddenly commits suicide without even leaving a note? What does it mean to lose someone and then replay their last days over and over, searching for clues?

Filmmaker Lee Han, who made a huge breakthrough with his 2011 drama “Punch,” a tale about a rebellious teen whose mother is a migrant from the Philippines, is making a strong comeback with another film about vulnerable teens and their families. Unveiled to the press on Tuesday, the film, titled “Elegant Lies,” succeeds in tackling the difficult issues of teen bullying and suicide with sensitivity ― while remaining a solid family drama.

The cast is almost impeccable. Veteran actress Kim Hee-ae, who has been mostly active in TV drama series, stars as Hyeon-sook, a single mother raising two teenage daughters while working at a big grocery store. Playing Kim’s aloof eldest daughter Man-ji is Ko Ah-sung, who appeared in Bong Joon-ho’s “The Host” and “Snowpiercer.” Teen actress Kim Hyang-gi, who played the bratty child in 2012 fantasy film “A Werewolf Boy,” stars as Man-ji’s younger sister and middle school student Cheon-ji, the protagonist of the film.

Based on author Kim Ryeo-ryeong’s 2009 novel of the same title (Kim is also the writer of “Wandeuk,” which director Lee’s “Punch” was based on), the film begins with Cheon-ji’s abrupt suicide. To Hyeon-sook and Man-ji, Cheon-ji was the sweet child of the family, who rarely complained and studied hard, while always trying to comfort her hard-working, often-weary mother. Struggling with guilt and anger, and not knowing why Cheon-ji chose to kill herself, the two women wonder whether there was something they missed or something they could have said or done.

The film is presented in a non-linear narrative, with flashbacks of Cheon-ji’s past that Hyeon-sook and Man-ji were oblivious to. Cruel acts of teenage bullying fill the screen, including a birthday party where Cheon-ji eats alone while the rest of the girls stay silent; they are in fact sending each other Kakao Talk messages about how pathetic and sad Cheon-ji’s situation is. Socio-economic background also plays a factor. Having a single mother who is financially struggling only makes Cheon-ji more vulnerable to bullying.

Lee does an impressive job of capturing the cruel side of adolescence as well as the terror of being an outcast while being a teen. Close-ups of Cheon-ji’s helpless face, as well as the ones of her classmates ― all looking uncertain and afraid ― make it hard not to empathize with the characters, even with Hwa-yeon (Kim Yoo-jung), the bully. Teen actress Kim Yoo-jung ― and her almost eerie visage ― is captivating as the troubled, manipulative teenager, who doesn’t get enough attention from her money-driven parents and is convinced that any friendship can be bought.

What’s disappointing is Ko Ah-sung’s performance, whose character learns about the indignity her late sister suffered only after her death. Her acting often lacks consistency and subtlety, particularly in scenes with Kim Yoo-jung, who plays Hwa-yeon. Kim’s memorable performance almost outshines Ko’s.

Kim Hee-ae is excellent as the grieving mother; her performance is understated but somehow believable, touching and honest. Heartthrob Yoo Ah-in, who played the protagonist in “Punch,” has a rather eccentric, flaky supporting role, while Chun Woo-hee, who played the tormented under-aged sexual assault victim in Lee Su-jin’s award-winning debut “Han Gong-ju,” also adds an important layer to the film as the guilt-stricken older sister of one of the young bullies.

Filled with mystery, drama and sensitivity, the film isn’t hard to watch, but many will find it heartbreaking.

“Elegant Lies” opens in theaters on March 13.

By Claire Lee (dyc@heraldcorp.com)