Kit (Brie Larson) is a lonely twenty-something dreamer who's reluctant to leave the comforts of childhood and fully embrace adulthood. But when art school sends her packing, Kit is forced to move back home with her parents and take a temp job in a boring office. Just when she's resolved to finally put her Care Bears aside and grow up, a mysterious salesman enters Kit's life and offers to give her childlike heart its greatest desire. Unicorn Store is a love letter to everyone's inner child, and a reminder that no dream is impossible.

Despite going through the motions of milestone events similar to couples at their stage, such as buying a house together, and having their first child - a daughter named Ellie - unmarried Matteo and Adrienne could probably not admit to either him/herself or to the other that he/she is truly happy with their life together. The emerging problems by these milestones only highlight existing problems, such as the issue of exes, and the intense dislike and mistrust between her mother Patty and him. A traumatic incident leads to both going on a metaphysical journey of their lives together - their future based on how their life has been so far, and a revisiting of their past and what key moments actually meant in knowing what they know now. Each goes into this journey with a different mindset due to their different beliefs of their current state of being. The questions become whether they will emerge from the journey at all, and if they do whether the journey itself will lead them to a path of true happiness as a couple/family.