This Channel 4 mini-series, directed by Peter Kosminsky, is a compelling work but with regards to the creation of Israel and the present day situations it is a tad one-sided. Or at least questionable in the sense that it is probably a bit too Pro-British and pro-Palestinian and anti-Israeli [though not anti-Semitic] without giving us an even-handed treatment of the history or the issues.
I'll admit I know very little about the history of the birth of Israel and the settlement of the Jews after World War II by the British in Israel. I too know little about the 1948 Palestinian exodus. And only until recently did I learn about the King David Hotel bombing or the Irgun or the Haganah. So I can't speak for the film's historical accuracy or the politics of the era.
However, I know movies and character development and I know when a movie works to present one side of the story at the expense of the other. The Promise does that and, therefore, is nowhere near as powerful as it could be.
The mini-series deals with a young British woman named Erin (Claire Foy) who goes to Israel in the present day to see off her Jewish friend who has joined the military. While there she stays with her friend's family [who live in a wealthy area of Tel Aviv] and each day reads her grandfather's diary, which he wrote while he was a British Sergeant in the the post-war phase  of the British Mandate of Palestine. Each day we see, as the film effortlessly flashes back in time, that he was right in the thick of things as the British soldiers attempted to aid the Jewish settlment and create Israel.
As Erin continues to read the diary she becomes more and more emotionally involved in her grandfather's history, which becomes fraught with daily dangers. Then she finds a key that her grandfather has stashed in the diary. Once she realizes the key belongs to a Palestinian family she becomes determined to find the family and return the key. But doing so is close to impossible and most certainly unwise when it becomes evident she will need to travel into places tourists don't travel; including Hebron and Gaza.
The story of her grandfather, named Leonard or Len (Christian Cooke), parallels her own adventure albeit with more bloodshed and intrigue with regards to the battles [both militarily and emotionally] that he fights with the Zionist groups that want the British and the Palestinians out of Israel. Both sections of the film deal with betrayals, violence and death.
I became interested in the series after I heard an interview on a Chicago radio station in which Tom Luddy said this series would never get play in the United States. So, curious as to why the heck not, I ordered it from Amazon UK. He's right. The reason is because most of the Jewish characters are presented as racist, suspect and superficial. Even the one Jewish character we are supposed to associate with seems a bit off; at one point he picks up a gun and shoots back at some Palestinians much to the chagrin of the main character. On the other hand, the Palestianian characters are all presented as a friendly people who are victims of the Zionist machinations. No doubt, many were victims - no one deserves to be run out of their homes. But at a point the Arab's own military push back should have been acknowledged.
There are two scenes in particular that really stand out and may not be credible. One is a scene in which Len's buddies get shot point blank by Zionist nationalists while a bunch of other Jews sit around a cafe completely ignoring the violence and sipping their coffee. Really? Another scene in present day Hebron presents us with young Jewish children throwing rocks at Palestinian girls while soldiers stand around impartial to the whole thing. Both these scenes feel heavy-handed.
The mini-series is undoubtedly effective at eliciting emotion. It is well acted and directed and at almost 6 hours it accumulates its dramatic effect and becomes a very engaging experience. But - besides the character portrayals - the other film's weaknesses include push-button conflicts that are telegraphed and obvious. Only rarely does the film achieve the kind of balance needed to make for a more heartfelt [and real] experience.
The Promise is recommended and anyone with an open mind should be able to look past the narrative actions and portrayals to see the larger picture - which is mainly about a young woman trying to fulfill 'the promise' of her grandfather toward a family he felt close to. But, if anything, the series is primarily an entry point to a larger conversation about Israeli's history, the role of the British in 1948 and the present day Israeli / Palestinian conflict.