Deception is at the heart of writer-director Lulu Wang’s “The Farewell,” a comedy-drama based on her own family’s experience surrounding the illness of her grandmother. But the film’s deception does not extend to its promise to warm the hearts of viewers. In that it succeeds without question.

Wang’s semi-surrogate Billi is played by Awkwafina. Billi has been living with her father Haiyan (Tzi Ma) and mother Jian (Diana Lin) in New York for years, and is almost fully Americanized. She’s just found out that she’s been turned down for a Guggenheim fellowship, though she keeps that to herself.

But there’s a larger secret in the family. Nai Nai (Zhao Shuzhen), the grandmother back in Changchun with whom Billi’s maintained a very close relationship, has been suffering from a bad cough, and when she undergoes tests, she’s diagnosed with terminal lung cancer. The results, however, are given to her younger sister (Lu Hong), who decides that the truth should be kept from Nai Nai, so that she can enjoy what time remains to her as normally as possible. So Nai Nai thinks she’s just suffering from the aftereffects of a bad cold.

Billi doubts the wisdom of the decision to keep her grandma in the dark, and her parents think it best, given her inability to keep her emotions in check, that she not come along to a reunion the family is preparing in Changchun, purportedly to celebrate the nuptials of Haohao (Chen Hao), the son of Haiyan’s older brother Haibin (Jiang Yongbo), to his Japanese girlfriend Aiko (Aoi Mizuhara), but actually to give everyone the chance to say goodbye to Nai Nai. Billi, of course, decides to attend anyway, and goes along with the family’s plan despite her reservations, though it’s hard for her to do so.

The wedding party, which Nai Nai naturally takes charge of, is the movie’s centerpiece, and it includes boozy speeches by many of the family members that straddle the line between celebration and sadness. Nai Nai remains ebullient throughout it all, and it’s revealed that when her husband was terminally ill, she kept the fact from him until he was at point of death (she’s since taken in an elderly man named Li as a roommate, who pads about the apartment); so the practice, it seems, is a sort of family tradition that’s apparently also an accepted practice in a culture from which Billi has become increasingly estranged.

There’s a goodly amount of poignancy in “The Farewell”—how could it be otherwise, given the utterly winning performance of Zhao, who entirely inhabits the part of the busybody Nai Nai, and a surprisingly affecting one from Awkwafina, who brings pathos as well as humor to Billi? But the remaining cast excels as well. Ma brings a tone of world-weariness to Billi’s easygoing dad that seems just right, particularly when joined to Lin’s turn as his no-nonsense wife, with whom Billi shares a potent dramatic moment about controlling one’s feelings. As for the comedy, it would be hard to outdo Han, whose terrified goofiness in the face of a marriage he’s obviously unready for culminates in a total collapse at the ceremonial meal. It’s the culmination of a celebration at which a great deal of alcohol flows.

Technically “The Farewell” is more utilitarian than artsy, but the Changchun locations bring a strong sense of authenticity to the story, nicely captured in Yong Ok Lee’s production design and Anna Franquesa’s cinematography. Alex Weston’s score can get a bit syrupy at times, but it’s not really an irritant.

Funny without getting coarse and touching without becoming mawkish, “The Farewell” is a moving tale of a young woman coming to terms with both her grandmother’s mortality and her own uneasy place between two cultures.