“It’s just like cleaning up a house, but there’s blood there,” Rose Lorkowski (Amy Adams) explains nonchalantly to her younger sister Norah (Emily Blunt) in “Sunshine Cleaning,” the new film from the producers of “Little Miss Sunshine.” Her cool, collected approach to such absurd proposals—a crime scene cleanup business, in this case—epitomizes what Big Beach Films continues to get right, despite its predictable recipe for indie flick humor.

The biohazard removal business shines as a beacon of hope for the film’s lovable, but not particularly successful, sisterly duo. Adams plays a once-popular cheerleader having an affair with her married ex-quarterback, ex-boyfriend Mac (Steve Zahn). Their son Oscar (Jason Spevack) is in desperate need of expensive, individualized private school enrollment thanks to his habit of licking walls at his current public school. Norah has even less to look forward to in the morning. In the words of her sister, “You don’t go to school, you don’t have a job, and you live with Dad”—the stubborn grandfather figure once again played by Alan Arkin.

Mac’s suggestion that Rose quit her day job as a maid and become a different kind of cleaning lady offers both girls a chance to turn their lives around. Through shared triumph over hardship—disposing of everything from a finger to a maggot-infested paper bag—the girls move from insulting one another to forming a substantial and trusting relationship.

The film’s premise, inspired by a National Public Radio report on two best friends’ real-life foray into the biohazard removal business, is refreshingly far-fetched. Every other aspect of the film, however, begs to be compared to Big Beach’s Oscar-nominated 2006 release, “Little Miss Sunshine.” From the Albuquerque setting to the overuse of the word “sunshine” to the pivotal presence of a dilapidated van, there is a lot we’ve seen already. Arkin’s grandfather character appears to have risen from the dead to star in yet another film, although this time it is he and not Greg Kinnear who is hooked on get-rich-quick schemes. Even the storyline follows the same arc as its predecessor. So which film deserves the title of “Sunshine?”

Surprisingly, the parallels between the two films work. Big Beach may be a one-trick pony, but the trick is excellent; the mix of quirky personalities, preposterous situations, biting sarcasm, and slapstick is every bit as effective as it was three years ago. The difference here is the increasingly somber tone of the plot. The “Little Miss Sunshine” pageant threatened a young girl’s self-image, but these characters’ decisions affect their entire futures. “Sunshine Cleaning” evokes less laughs and perhaps more reflection than its counterpart, but the somber moments are more affecting, and ultimately more relatable.

What the new “Sunshine” has that the old lacks is, quite simply, Norah. Brash and deadpan, her idea of lulling her nephew to sleep is telling him a bedtime story about a man with OCD. British actress Blunt—best known for her role as the bitchy co-worker in “The Devil Wears Prada”—adds just the right amount of sensitivity to undercut her character’s sarcastic wit, which would grow tiresome in the hands of a lesser actress.

The more subdued Rose is touching but less convincing. Even though she calls herself “a fucking loser,” her insecurities don’t always seem genuine. Her puppy dog eyes bewitch many of the film’s characters, but fail to persuade the audience that her setbacks are truly as grave as she believes them to be.

If the film really is “Little Miss Sunshine 2.0,” its greatest success lies in the updated evolution of the central characters. “Little Miss” chronicled the journey of some lovable protagonists accepting the slow collapse of their odd dreams—writing a book, winning a pageant, becoming a pilot. “Cleaning” does this too, but then allows the characters to find salvation in the unlikeliest of places, breaking self-destructive cycles and pursuing new paths to success. We’ve seen most of this movie before, but the extra mile taken by “Cleaning” is well worth the journey.