The end of December brings a greater flood of films to cinemas than any other time of the year, as serious-minded Oscar contenders fight for screens against blockbusters seeking to draw business from the fact that millions of Americans are basically off work for two weeks straight. The harrowing new Julia Roberts thriller “Ben is Back” and the spectacularly joyous Emily Blunt star vehicle “Mary Poppins Returns” offer outstanding examples of both ends of that spectrum while standing as two of the best films of the year.

“Ben” stars Roberts in her best role in years as Holly Burns, a mom in a small town in upstate New York who is happily ensconced in life with her second husband Neal (Courtney B. Vance) and their two young children, as well as her teenage daughter Ivy (Kathryn Newton) from her distant first marriage. The movie opens on Christmas Eve morning with Holly supervising her youngsters and Ivy as they prep to perform in their church’s Nativity play that night.

All seems well with the world, until Holly and her kids arrive home to find a shocking sight: her teenage son Ben (Lucas Hedges) is standing in their driveway. What should be a run of the mill moment for such a happy, seemingly stable family instead prompts instant fear and concern, for Ben has nearly ruined their lives in recent years with his never-ending battle against opioid addiction.  

Holly at first embraces Ben and his claim that his sober living program and sponsor allowed him to come home for Christmas because he’s been doing so well in rehab. But Ivy is instantly skeptical and sends Neal texts begging him to rush home and put a stop to the visit before Ben can cause problems again.

Neal wants to send Ben straight back to rehab, but in the spirit of Christmas, allows him to stay through Christmas as long as Holly watches his every move, including sleeping on his bedroom floor to make sure he has no chance to take drugs. Ben agrees to the strict terms and all seems well, but when he convinces Holly to take him on a gift-shopping trip in town, one bad apple after another from his past runs into him.

Soon, it’s clear that all manner of the town’s most verminous people are teaming up to get revenge for the havoc he wreaked during his years of addiction, and both Ben and his family are in a great deal of danger. It’s up to an increasingly horrified Holly and Ben to find a way to make things right before Christmas morning.

“Ben Is Back” centers largely on the powerful dynamic between Holly and Ben, and the movie is blessed to have Roberts and Hedges giving two of the best performances I’ve seen in years. From their early happy moments through the slow-building sense of dread and onward into the stark emotional power they display as they frantically race through a seemingly sweet town that Holly learns is full of unspeakable evil, these two offer a master class in acting.

Just 23 years old, Hedges has already been Oscar-nominated for 2016’s “Manchester by the Sea” and has already earned a Golden Globe nomination for his excellent performance in “Boy Erased” (also highly recommended and in theatres now). But he surpasses his fine work in that film here, working under the guidance of his father Peter Hedges, who wrote and directed “Ben” and gives the film a nerve-jangling energy  that pays off with a thoroughly riveting third act.

“Ben” isn’t sunny entertainment for the whole family, but it shines a sad light on what millions of American families are going through right now as they face the devastating impact of addiction on their lives. For those seeking great acting, unpredictable twists and some unexpected heart, it fills the bill.

Meanwhile, “Mary Poppins Returns” brings the magical nanny back to life with Emily Blunt replacing the now-octogenarian Julie Andrews in the role, and Broadway star Lin-Manuel Miranda of “Hamilton” fame basically filling the original’s Dick Van Dyke role as Mary’s sidekick, Jack. The little boy from the original film, Michael, has grown up to be a very sad widower and father to three young kids of his own.

When his bank threatens foreclosure on the only home he’s ever known, Mary floats down from the sky to re-enter his life by offering her services as nanny to his kids. Michael and his sister Jane have five days to find their late father’s shares in the bank and save the family home, a quest that Mary and Jack grandly lead the children into joining.

I’m saying as little as possible about what happens from there, because I’m happy to report that the new “Mary” is in every way as wonderful as the original Andrews classic. Thanks to the fact that special effects have improved so greatly in the 54 years since the 1964 original, this might even be better— and every time you think the film can’t possibly get more inventive, it does so tenfold.

Director Rob Marshall brought the musical genre roaring back to life with 2002’s Best Picture-winning “Chicago” and delivers an even greater artistic achievement here. Writer David Magee was a perfect choice to write this, having scripted the Oscar-worthy child fantasies “Finding Neverland” and “The Life of Pi” previously.

Perhaps most refreshingly, “Mary” also knows to bring back the classic hand-drawn style of the original for its animated sequences, and the entire film steers clear of sneaking in a parade of PC social messaging — something that countless other children’s films need to learn to avoid. This movie is unabashed pure joy that anyone who’s human and alive will come out of feeling great. 

“Ben Is Back”: A

“Mary Poppins Returns”: A