The Promise - Season 1

In 2005 gap year student Erin and her mother are clearing out the belongings of Erin's dying grandfather Len when Erin discovers his diary. Having accompanied Jewish friend Eliza to Israel Erin begins to read it,starting with the horrifying liberation of Belsen,which gives Len empathy with the Jews. A professional soldier he is involved in the dispute in Palestine between the liberated Jews seeking their promised land and resentful Arabs.He falls for a Jewish girl,Clara,and reluctantly agrees to spy on her father Leo,a suspected Jewish dissident. His loyalties are torn when he sees comrades massacred in an ambush by insurgents. Erin finds Eliza's family also have divided loyalties,her brother Paul having Palestinian sympathies. He takes her to a cafe where a suicide bomber strikes.

Erin and Paul survive the blast,Paul's parents commenting on the irony of his falling victim to the Palestinians,whose cause he supports. His great-grandfather was one of the bombers of the King David Hotel,in which Len is injured.Len suspects involvement by Clara,who tried to prevent him from going to the hotel but she denies it. As the British begin Operation Bulldog,to flush out terrorists in Tel Aviv,Len is dismayed by the brutality shown to the locals. He also steps in to prevent Mohammed,the Arab who provides the company with tea,from being bullied and befriends Mohammed's family,who resent the Jewish settlers. He has his photo taken with them and Erin finds it,setting out to trace any surviving members. Len ends up in hospital after gunmen attack him and his colleagues.

Len survives the attack and is visited in hospital by Mohammed,to whose son he teaches Maths whilst recuperating. He is asked to persuade convicted terrorist Avram Klein to appeal against his execution to buy time as the army fears reprisals if he is hung. Len visits him and Klein warns him there is a spy in the British camp. After Clara is tarred and feathered for collaborating with the British Len and two colleagues are captured by the Jews who want Len to join them. He refuses and is released but his friends are murdered since Klein is hanged. Erin gets close to Paul's friend Omar but the Meyers disapprove of her bringing him home. This induces her epilepsy and she notes that Len also suffered from fits. She travels to Hebron to see Mohammed's house but walks straight into conflict and is arrested.

Erin is arrested by Israeli soldiers but freed after Paul intervenes. They stay overnight in the army camp,which is shelled by Palestinians and next day, having told Paul about the diary and how she wants to locate Mohammed's family out of respect to Len,she learns that they have moved into the war zone of Gaza. She gets Omar to drive her there,ending up in the house of the cafe bomber,to which Israeli soldiers,including Eliza,come with the intention of blowing it up.Erin,echoing her grandfather's courage,chooses to stay to comfort the little girl of the house and meets an elderly lady,Jawda,who is Mohammed's daughter. In 1947 the state of Israel is officially recognized and the British prepare to withdraw.Len is horrified to witness the massacre of an Arab village by Jews,including Clara,who nonetheless claims to still love him and does his best to take Mohammed and his children to the docks and safety as the exodus of Arabs from Tel Aviv begins. However the family members are separated and Mohammed's son Hassan killed. As he dies he gives Len a house key to give to his father but Len is arrested for deserting his post to help the Arabs and never gets to see Mohammed again. Erin now has that key and gives it to Jawda before going back to England,Paul commending her for her bravery.On her return home she tells the dying Len that she has returned the key to the family. He seems to understand.