Actors Kieran Culkin and Jesse Eisenberg have reunited on the red carpet at the London Film Festival to launch their latest film, a comedic spin on family and grief.

Culkin is best known for playing Roman Roy in the Emmy-winning Succession, while Eisenberg shot to fame playing Mark Zuckerberg in 2010's The Social Network.

The pair's new film A Real Pain, which is written and directed by Eisenberg, has been widely praised at film festivals and could have an outside chance of making waves in awards season.

Although the film looks like a standard bro-comedy from the trailer, it punches well above its weight and has more depth than audiences might expect.

Eisenberg and Culkin play two cousins who have very different temperaments. While Eisenberg's character David is cerebral and family-oriented, Culkin's Benji is haphazard and rebellious.

The pair are brought together for a visit to Poland following the death of their grandmother, a Jew who escaped the Holocaust and built a new life in the US.

Using the money their grandmother left specifically for the trip, David and Benji travel across the country together as part of a tour group, breaking off occasionally to find out about her life, while processing their grief in different ways.

The film also stars British actor Will Sharpe as the tour guide and Dirty Dancing's Jennifer Grey as one of the other tourists.

The two US actors walked the red carpet ahead of the film's UK premiere at the London Film Festival.

The film has received broadly positive reviews from critics. Tomris Laffly of Harper's Bazaar described it as "understated, funny, and gradually heart-swelling", adding: "Expect to hear about this one next award season."

A Real Pain is a "frequently laugh-out-loud funny odd couple road trip movie whose emotional wallop sneaks up and floors you," added the Hollywood Reporter's David Rooney.

Culkin is praised for a "career-high performance" by Deadline's Damon Wise. "Benji is a gift of a role, the kind that makes movie stars, and Eisenberg generously hands it to Culkin on a plate."

There has been some consternation in awards circles, however, that Culkin is campaigning in the supporting actor category, when many consider him the film's lead.

Vanity Fair's Richard Lawson was cooler on the film, commenting A Real Pain "is slighter than expected and is thus easily overwhelmed by Culkin’s high shtick".

"Sure, this film has conventional beats," acknowledged Ema Sasic of Next Best Picture, "but that won’t keep you from enjoying it."

Kristy Strouse from Film Inquiry agreed: "Amid the comedic elements, the film skillfully delves into the poignant contemplation of loss."

Despite being a tight 90 minutes, A Real Pain packs in a lot of issues, hooking viewers in with snappy jokes which mask deeper themes that gradually emerge over the course of the film.

For viewers who found last year's awards player The Zone of Interest hard going, A Real Pain tackles a not-dissimilar subject in a much more accessible way.

It is beautifully directed, bringing viewers along for the ride on a trip across Poland.

The country's often charming scenery in the early parts of the film starkly contrasts with an affecting later visit to the Majdanek concentration camp and the house their grandmother had to leave behind.

Asked about working with Culkin on A Real Pain, Eisenberg told Esquire: "I really don’t like improv, but Kieran is such an unusual performer.

"He would say things that deviated from the script, and a lot of times they were just better.

"When I first heard something that was a deviation, it rang a false note for me because I had to look at the script for so long. But in the editing room we ended up going with some of Keiran’s improvs because they just felt natural to him."

Culkin is one of several actors from Succession who have found huge success as a result of starring in the acclaimed HBO drama.

The series focused on a media mogul, played by Brian Cox, and his children, who are battling to take over his empire. It was partly inspired by Rupert Murdoch's family.

Culkin's former Succession co-star Jeremy Strong also has a film at the festival - the Apprentice, about Donald Trump's early years as a real estate tycoon.

And the show's other former cast members Sarah Snook and J Smith Cameron have both recently starred in shows in London's West End, as has theatre veteran Cox.