NOTE: This spoiler was submitted by Kitty
The movie opens with a card stating it’s “based on a true lie.”
Billi (Awkwafina) lives in New York with her parents Haiyan (Tzi Ma) and Jian (Diana Lin) but remains pretty close to her grandmother in China, Nai Nai (Shuzehen Zhou) and talk on the phone all the time. Billi gets a call from Nai Nai in the morning in NYC and gets fussed over like all grandmas do over their grandkids. What Nai Nai doesn’t tell her is, she’s in the hospital for some tests accompanied by her sister, Little Nai Nai (Hong Lu). They agree they’ll talk later and Nai Nai goes for a CT scan. Her sister goes to talk to the doctor afterwards and then tells Nai Nai there’s nothing wrong, just “some benign shadows.”
Billi is not really doing well in her life, and while on the phone with Nai Nai later on that day, she opens a letter that says her application for a Guggenheim fellowship has been rejected. She keeps this information from Nai Nai and everybody else.
Billi goes to visit her parents and her mom gives her grief over the fact she doesn’t have any money or seems to be moving forward with her life. She also tells her she and Haiyan are leaving for China the next day because their nephew Hao Hao is getting married to Aiko (who is Japanese and doesn’t speak Chinese) and Billi is not to accompany them. When Billi questions why the wedding is so rushed, Jian hushes her as Hayan is sleeping. Billi asks why, since it’s only 6:00PM, but Jian waves her off.
Billi then goes in the bedroom where her father is sitting on the bed. She asks what’s wrong because she can tell something is not right, and questions whether he’s been drinking, which he denies. Hayan eventually tells her Nai Nai has stage four lung cancer and the wedding is just an excuse for everybody to go over there and see her. Billi says she must go, but her parents refuse. Jian says they’re not telling Nai Nai about her condition because in China families believe if you tell someone they have cancer, they die, not because of the disease but of the fear. The reason they don’t want her to go is, Billi’s emotions show on her face and Nai Nai will know something is wrong.
Billi eventually shows up in China, much to her parents’ dismay and Nai Nai’s delight. Jian questions once again where Billi got the money for the plane ticket, but Billi doesn’t reply, and shows her instead she can hide her feelings. From then on, it’s all about the wedding planning and the differences between America and China, with Jian and YuPing (a distant relative) sniping back and forth about life opportunities in the two countries. Nai Nai cuts the arguments short by saying they can’t criticize China, no matter what.
Nai Nai teaches Billi some form of walking/breathing exercise that involves grunting out loud “so you can do it alone when you go back to America.” Billi struggles with the “we’re not telling Nai Nai she has cancer” thing and keeps bringing it up, only to be shut down again and again. Eventually, after an evening of heavy drinking by the immediate family, Nai Nai goes to the hospital after a coughing attack. Once again, Billy brings up with the doctor the situation with Nai Nai, and he also advises against telling her about her condition. He tells Nai Nai the cough is leftover from the pneumonia she’d had earlier in the year and it’s a secondary infection. He agrees to change her medicine and orders an X-ray.
Billi finds her father and uncle Haibin (Yongbo Jiang) smoking at the hotel where they’re all staying, and she brings up the lying again. Haibin explains that the difference between living in America and in China is that in America people believe their life belong to themselves, whereas in China people’s lives are part of a whole, of a family, of society, and therefore it is the family’s duty to carry the emotional burden of the cancer knowledge FOR Nai Nai.
Billi tells her mother she wants to stay in China to take care of Nai Nai but Jian is not having it and once again berates her daughter since she “can’t cook, can’t clean, what are you going to do?” Billi brings up she couldn’t come to China when her grandpa (Ye Ye in Mandarin) died and how that affected her. Jian once again dismisses her.
Before the wedding, Nai Nai asks Billi to be nice and courteous with the wedding guests, smiling and greeting them and agreeing to sing if called to do so. On the wedding day, after arguing with her sister for having to wait until Monday for her X-ray results, Nai Nai gets Billi’s attention and gestures for her to smile, so Billi does what she’s been asked to do and is nice to everybody. However, at the time of the speeches, Haibin, father of the groom, goes up on stage and basically loses it and starts crying which he attributes to being “very happy.” Billi also goes up on stage and makes a speech, aided by her dad who tells her the Mandarin Chinese for “congratulations.” They also do karaoke together to “Killing Me Softly.” After a raucous drinking game, Hao Hao starts crying inconsolably.
When the time comes for the family picture with the bride and groom, Nai Nai questions why the groom is crying and once again she’s told “tears of joy.” Little Nai Nai asks if they can take one with her camera, which Nai Nai says she gave to Mrs Gao (their maid) to hold. When Little Nai Nai asks where Mrs Gao is, Nai Nai says she sent her to the hospital to get the X-ray results.
As soon as the picture is taken, Billi hightails it to the hospital to intercept Mrs Gao, which he does, only to realize Mrs Gao is illiterate and doesn’t know what the test results are. Then Billi and Little Nai Nai take the results to a shop to have them altered to read “benign shadows.” When the shop employee questions what that means, Little Nai Nai snaps, “It’s not terminal!”
Nai Nai gets the test results and tells them all off, “you worried for nothing! I told you I was fine!” After that, she meets with Billi before she leaves and gives her an envelope with money, because she’d given one to Hao Hao so Billi gets one too. When Billi opposes, as she didn’t get married, Nai Nai says that’s more the reason for her to accept it, and to not spend it on something sensible like the rent, but to get herself something nice. Billi then confesses to Nai Nai she missed out on the fellowship, and Nai Nai advises that it’s not so much what you do in life, but the way you do it.
Billi and her parents are leaving and Nai Nai hugs Billi for the longest time before letting her go and assuring her they’ll see each other again. Billi is back in New York City, unsure of what to do, and while walking down the street, she stops in her tracks and grunts loudly, like Nai Nai taught her. The movie ends.
We’re shown a video of the actual Nai Nai, who’s still going strong six years after her stage four cancer diagnosis.