Don’t Think Twice” is a comedy about comedy, but with a perfectly written strand of bittersweet drama at its core, brought to life by a believable and hilarious ensemble cast. It follows the escapades of The Commune, a tight-knit improv group at a crossroads when they lose their performance space, and one of their group gets his big break. It’s a hilarious but moving look at the realities of navigating the stages of adulthood, and one of my favorite films of the year.

“Saturday Night Live” is thinly disguised as “Weekend Live” in this movie, but whatever it’s called, the show represents the golden career opportunity for comedians, as writers or performers. Of course, when one of the friends gets his big break, it sends shock waves through the group, which includes Keegan-Michael Key, Mike Birbiglia and Gillian Jacobs.

Birbiglia, who wrote and directed the film, plays Miles, the group’s founder, a guy who also teaches improv, who pines for the one time he almost got on “Weekend Live,” and who claims he taught people “everything they know” quite often. He says this most often of Jack (Keegan-Michael Key,) the guy who lands an audition and a part in the Holy Grail of comedy TV, “Weekend Live.” Their rivalry is obvious, but Samantha (Jacobs), who is Jack’s girlfriend in addition to being a performer in The Commune, has a far more interesting and poignant reaction to this turn of events.

Jack’s success embitters some members while galvanizing others into action. As their beloved venue, Improv America, is being turned into an Urban Outfitters, the group faces an uncertain future. Jack’s success shines a glaring light on the opportunities left for everyone. One member faces mortality when his father has a serious accident, and others finally begin to look for happiness in potential relationships.

I love this movie because it has so many perfect scenes describing the points in life where you consider your options, face realities and re-evaluate your definition of success. All of the characters basically want the same thing — to be famous comedians — but not all of them are going to be. The way they keep going, in various ways, was so much fun to watch. It was sometimes depressingly honest, but when people really look at what art means to them and what they can do with their lives, it becomes truly inspiring.

“Don’t Think Twice” hits the funny and dramatic notes perfectly, and the relationship between Jack and Samantha is unusually, wonderfully complex. I don’t often use this silly term, but this is a great date movie for that reason. Samantha is a fantastic female character, and it’s rare you get to see an adult woman navigate a relationship the way she does in this film.

Writer, director and star Mike Birbiglia must be drawing from some real-life experiences here, because the whole film just rings true. Every scene has something hilarious in it, and every scene has some perfectly honest detail. Miles’ crappy loft has sheets tacked over the windows as curtains, but they are fitted sheets. When a character’s father gets injured and they visit him, all his friends soon take turns on a perfect impression of his pitiful voice. The script is note perfect.

You may or may not see yourself in these characters, but their delusions and their realities are rendered vividly in this short, (bitter)sweet film; don’t think twice about going to see it.

“Don’t Think Twice” is playing exclusively at the Crescent Theater.