How one reacts to Jennifer Aniston’s tormented lead character in the independent film Cake will ultimately decide the film’s cumulative impact. Personally, I admired it, even though the role (and entire film) is dour and a bit strained in its narrative progression. Be warned: those looking for Aniston to channel some sort of post-Friends warmth or Horrible Bosses type ironic comedy will be left sorely lacking.

We first meet Aniston as Claire, a woman dressed in frumpy, drab clothing and only speaking to incite the tensions in her chronic pain rehabilitation group when the topic of another member’s suicide is brought up as therapy. Her brutally honest diatribe draws tears from the rest of the group and completely sabotages the intentions of the moderator (Felicity Huffman).

We then follow her through her day, as she’s chauffeured around by housekeeper and general nurse Silvana (Adriana Barraza), choosing to lie down in the car due to the constant pain she endures. Complete with scars on her face and the incessant dive into medicine cabinets where she steadily self-medicates via a weird cocktail of Oxycontin and Vicodin, Claire is literally sleepwalking through her existence.

Signs of life begin to sprout in her, though, as she becomes interested in why her fellow group member (Anna Kendrick) committed suicide and insinuates herself in the woman’s old life, including meeting her husband (Sam Worthington) and young son (Evan O’Toole).

Along the way, the film interjects moments of Claire’s shifting mental state as she carries on imaginary conversations with the dead girl or flashes of a horrible car accident spray across her dreams. These out-of-body experiences add a level of uncertainty to the film and provide it with its most demanding and interesting sections, questioning whether Claire is crazy or simply the dulled victim of too much medicine mixed with alcohol.

Much has been made of Aniston’s “ugliness” in Cake, eliminating make-up and slipping into a unrecognizably bleak character light years from previous on-screen roles. The cosmetic appearance is jarring, but she also buries deep inside a challenging role. Isn’t this what all good actresses should do?

Directed by Daniel Barnz, from a script by Patrick Tobin, Cake does have its faults outside of Aniston’s strong central role. There are moments when the film seems to be following the prototype of every raw indie drama of the 1990’s, wallowing in the empirical themes of white suburban angst and unexplained emotional trauma. It doesn’t have anything especially enlightening to say about any of its subjects. There’s one too many “name actor” cameos that pop up for a single scene as if they’re happy to be slumming in a small film, and the visual schematic is quite bland.

Regardless, the main reason to seek out Cake is for Aniston’s genuine and dynamic performance, full of emotional distress. She portrays a woman dealing with serious issues who not only wants to suffocate any hints of real emotion that swell inside her, but make the lives of everyone else around her just as painful. And she does it well.

Cake opens in limited relase at the Angelika Dallas and Angelika Plano on Friday, January 23.