There are very few movies that depict Seder nights. There are even fewer that do so with an affectionate and intelligent sense of the celebration's variety, or the way that it brings out the best and worst in Jewish family dynamics. The filmic potential is abundant but yet to be explored in the way that the British director Gurinder Chadha limned American Thanksgiving dinners in her charming What's Cooking or the Indian director Mira Nair celebrated a classic Punjabi Monsoon Wedding.
Of course, films with explicitly Jewish subject matter are surprisingly rare given the historically disproportionate presence of Jews in film-making. If you discount films that deal with the Holocaust - and there are fewer of those than people believe - such works are rare indeed.
Even, or rather especially, when all the major Hollywood studios were led by Jews, Jewish film-makers were wary of bringing any overtly Jewish elements into their work, let alone any depictions of religious practices. British-Jewish film-makers also seem to have had their own cultural and business reasons for avoiding stories that might bring attention to their ethnicity and religion.
First-time writer-director Yoav Factor therefore deserves much credit just for attempting to represent a slice of modern British-Jewish life and for making a Seder the dramatic focus of a film.
He and his production team are also to be congratulated for the remarkable, counter-intuitive casting of Reuniting the Rubins. To depict three generations of the Rubin family, Factor has collected an unlikely but inspired group of talented, mostly non-Jewish actors who, in the main, are completely believable as north London Jews.
Rhona Mitra, for example, is a part-Indian actress best known for action flicks, including a starring role in the B movie, Doomsday. Honor Blackman has been a cult figure since her roles in Goldfinger and the Avengers television series. And Timothy Spall is one of our great character actors and justly renowned for his superb performances in Mike Leigh films like Topsy-Turvy, All or Nothing and Secrets and Lies.
Spall it is who plays Lenny, the sixtysomething head of the Rubin family, a middle-class widower who has recently retired and is about to go on a round-the-world cruise.
His surprisingly youthful, thickly-accented mother (Blackman) does not want him to leave and contrives to fall ill on the day he boards the ship, then makes a miraculous recovery after he rushes back from Southampton to be at her bedside. Their interaction is supposed to be antic and cute but falls flat in a sign of things to come.
Holocaust survivor Gran yearns for her dispersed family all to be in one place. So she buys the family house in which her son and his four now-adult children grew up and begs Lenny to bring them all home for Passover. He is reluctant because he feels it is an impossible task, but he gets to work when she becomes genuinely ill.
Lenny's oldest son Danny (James Callis, who does happen to be Jewish and is known for his role in Bridget Jones's Diary) is a ruthless businessman. Another son is a buddhist monk in London.
The third (Hugh O'Connor) has become a Chasid at a yeshivah in Jerusalem. Lenny's daughter, Andie (Mitra), is a heroic left-wing activist who lives in Africa and campaigns against Danny's company.
All disapprove of the others, but eventually they agree to come with their respective families for a house-warming dinner and perhaps for Passover the next day.
Unfortunately both the process of rounding them up and the interactions that follow are almost entirely bereft of drama or humour. The film has neither the required wit nor grit, thanks to a rather amateurish screenplay. All the characters are cartoonish where they have any life at all.
It is a shame because Reuniting the Rubins fails to take advantage not just of the talents of its fine cast, but also the opportunities offered by its subject matter.