Writer/director Shana Feste’s new film “Boundaries” doesn’t really stray far from the traditional road movie formula.

It’s predictable, at times is a little too quirky, and sags a bit in the middle act.

Yet “Boundaries” works, largely because of the cast – led by Christopher Plummer and Vera Farmiga. As a bickering father and daughter, Plummer and Farmiga are able to get way more mileage out of the script than one might expect – making the film somewhat passable.

Farmiga plays Laura, a neurotic single mom trying to raise her awkward teenage son Henry (Lewis McDougall). 

Things are further complicated when Laura’s estranged, pot-dealing father Jack (Plummer) is kicked out of his nursing home. The only place left for Jack to stay is with Laura’s younger sister JoJo (Kristen Schaal), but that means Laura and Henry have to drive him from Texas to California.

The simple trip becomes anything but as Jack sees it not just as a chance to reunite with his daughter and grandson, but sees it as a chance to sell some o his product to his loyal customers.

The cast also includes Christopher Lloyd (it’s really fun to see him again) and Bobby Cannavale in pretty much the same kind of role he’s played in every other film in the last five years.

Road movies tend to work better when these supporting casts are more memorable, which for the most part isn’t the case here. Fortunately, every time it feels like the film is coming off the rails Feste finds a way to veer it back to its strength – the chemistry between Farmiga and Plummer.

Farmiga works hard, even though she is given a character with way too many ticks (her obsession with taking care of every stray animal she sees is a running joke that quickly wears out its welcome), but still manages to create a character that rises above the script’s many flaws.

Plummer fares better, in a role you can tell he had a lot of fun playing. It’s a side of the Oscar winning actor we haven’t seen that often and I hope we see more.

His week is enough to life “Boundaries” slightly above mediocrity. You may have seen most of this before, but Plummer makes the familiar journey well worth it.

Starring: Vera Farmiga, Christopher Plummer

Directed by: Shana Feste

Rating: Rated R for drug material, language, some sexual references and nude sketches

Playing at: Regal Hollywood Stadium 27 in Nashville, AMC Thoroughbred 20 in Franklin, Tenn.

Grade: B-