As Dolly Wells’s rough-hewn, heartful, film debut opens, Lillian (The Meyerowitz Stories’ Grace Van Patten in a star-making turn) and her boyfriend Nate are breaking up on account on her shocking lack of adulting skills.

Her absent father, who is busy with his new girlfriend in France, is well connected enough to find the aimless Lillian a spare room with a musician friend and his partner, Julia Price (Emily Mortimer), a reclusive novelist.

Within days, Julia’s husband has walked out leaving the two nightmarishly mismatched women to exchange a series of terse handwritten house rules. Timm Sharp’s George, a crumpled dog-walker who lives in the basement, is rather more vocal on Lillian’s many shortcomings as a houseguest, what with the footprints on the wall, toothpaste on the bathroom mirror, and the use of Julia’s toothbrush.

The “entitled oaf” as she is unaffectionately known is required, in lieu of rent, to make dinner and water plants for Miss Haversham, as she calls her host. She’s not happy about it.

Slowly, the angry written exchanges coalesce into something like friendship, although there is more to Lillian and Julia’s relationship than the former realises, a history that is hinted at during a series of appealing literary cameos from authors Zadie Smith, Martin Amis and Jonathan Ames.

Doll & Em co-creator Dolly Wells re-teams with her longtime collaborator Emily Mortimer for this warm, engaging shaggy dog tale of young adulthood. Grace Van Patten’s Lillian, the messiest, most facepalm-inspiring protagonist since Lætitia Dosch’s Jeune Femme, is a marvellous creation.

Spoiled, callow, tactless and yet somehow lovable and vulnerable, she repays her fiercely guarded host by attempting to make a documentary about her: “Hey Julia, would you be okay with me making a documentary about you? I know I haven’t read any of your books or ever sat through a whole documentary?” It’s about as polite as Lillian gets. DOP Ryan Eddleston makes terrific use of the Bedford-Stuyvesant setting.