Transatlantic (Netflix) is a strange series, and one that gets better as it goes on. It is set in France after the German invasion and its unbelievable story of heroism, incompetence and a bunch of refugee surrealists is substantially true. And shot through with humour. World War II is easy; comedy is hard.

You have to be careful with the surrealists. Particularly when dozens of them are living in a French chateau and giving great parties. Some of them are refusing to co-operate with heroic plans to save them from the Nazis. Tempers fray and lovers quarrel. In the middle of one row, an exasperated boyfriend, who isn’t trying to be funny, shouts: “Don’t make this about the Chagalls!”

Transatlantic is a modern depiction of war. That is, it allows the presence of gay men, black people and women activists to be included. In this way it is pretty educational; at least it was for me. I had never heard of Varian Fry, an American Protestant who risked his life providing travel visas for refugee artists, mostly Jewish, from Nazi Germany. He saved about 2,000 lives this way. He was also a gay man.

The other American is Mary Jayne Gold (Gillian Jacobs), the daughter of a millionaire, who uses her generous allowance to help support Fry’s American Emergency Rescue Committee. The real Mary Jayne had toured Europe in her own plane. In this series she is reduced to driving her own Mercedes.

Transatlantic is modern in another way: its concentration on refugees. Here they are camping on the beach, close to starvation and waiting for boats to take them to freedom. When the ports are closed by the Vichy police — almost comic figures reminiscent of the BBC sitcom ’Allo ’Allo — they try to walk to Spain over the Pyrenees.

In the midst of all this are thousands of African soldiers, recruited from the French Empire, and now wondering what this war will mean for them.

This all happens well before the US entered the war. Both Varian (Cory Michael Smith) and Mary Jayne are outliers, fighting their native country as it continues to adhere to a strict policy of “America First”. America doesn’t want a whole lot of mostly left-wing, mostly Jewish refugees, even if a large proportion of them are geniuses who will go on to help create post-war American culture.

This is great material, first publicised by the writer Julie Orringer in her novel The Flight Portfolio, and brought to the screen by Anna Winger, who has serious form with series such as Deutschland and Unorthodox. But Transatlantic is not a great TV series, despite its considerable virtues. Its tone is uneven. You may not want to hack your way as far as episode 4 — there are seven in all — although you will be helped by the glamour of location, the beauty of the production design and the drama.

Casablanca this ain’t. But if you like World War II dramas and shocking truths, then this one is for you.