The simplest stories can often be the most revealing.

Grandma, the new independent comedy from Paul Weitz, opens in limited release this week as a dynamic and bombastic comedic vehicle for star Lily Tomlin. Its small and simple story allows for very big and complicated characters to grow onscreen.

Ellie (Tomlin) is a poet and professor, living alone after the death of her longtime partner. She’s quickly presented as a total firebrand as evidenced by her opening breakup with her new girlfriend, Olivia (Judy Greer).

After the dust settles from that argument, Ellie is surprised by her granddaughter Sage (Julia Garner) who beats down her door asking for $600 so that she can afford to abort an accidental pregnancy with her stoner boyfriend Cam (Nat Wolff). Ellie, however, has cut up her credit cards in a fit of anti-establishment rebellion and is waiting on some lecture payments so she hasn’t got the money either.

It’s up to Ellie and Sage to set out on a journey through both of their lives in order to find a benefactor for Sage’s abortion without letting her mother and Ellie’s daughter find out about their predicament.

This very simple plot structure – a clear goal and the journey to accomplish it – allows Weitz a tremendous freedom to explore his two leads. The structure also presents a delightful parade of characters from each of the ladies’ pasts that are both revelatory and entertaining thematic devices in their own right.

In a tight 78 minutes, Grandma is a marvel of storytelling and filmic efficiency. Weitz gets us into the story as late as he can and gets out as early as possible without wasting time on anything that will distract from his main story and ideas.

With little time paid to anything other than the main story, there’s a tremendous burden placed upon the film’s two leads to reveal the depths of their character through performance. Both are more than up to the task. It’s not surprise that Tomlin dominates the film in a role that’s written as a tour de force and that she swallows and spits out with the verve of a true legend.

It’s Garner who is the real surprise here as she presents a millennial that is both extremely fragile and totally fearless – a perfect representation of the generational contrast to the old battle axe that his her grandmother.

But this remains Tomlin’s show and what a show it is. In her first leading role in more than 25 years, Tomlin proves to all those who may have forgotten why she’s established herself s a comedic legend in her 40+ years of acting. This feels like a career-capper for Tomlin: a character that affords her the ability to utilize her entire toolbox as an actress – but one that hopefully lead to a career renaissance instead.

With such compelling leads, Grandma, doesn’t need to do anything fancy to get in their way, and Weitz doesn’t let it. He keeps the story simple and allows both his main characters and supporting characters to dominate and further heighten and explore his themes.

In this case, depth is found right on the surface of the story.