If you've seen Amélie, this is in similar vein: third-person narration, quirky characters, running gags and a chirpy, inquisitive central character. The main difference is that fewer people get spattered with intestines in Amélie.
Mathilde is an orphan left lame by polio in infancy. Her fiancé, a soldier, shot himself through the hand in order to get sent home from the Western Front, but was sentenced instead to walk out into No Man's Land as a punishment for his deliberate self-mutilation. Mathilde, in 1920, is convinced that he is still alive and sets out to investigate the mystery surrounding a trench called Bingo Crépuscule with the aid of a diminuitive private detective, his daughter, a Corsican prostitute and a dog named Chickpea.
It should be unremittingly schmaltzy, but has enough humour and genuinely enthralling plot to redeem itself.
It's interesting to see the First World War from the point of view of the French; one sees - OK, I watch - lots of films about the British and German troops, but very little about the poor old poilus whose countryside we were all churning up.
I only worked out the significance of the 'Albatross' a few beats ahead of the exposition, and smacked my forehead as I realised what was going on, how unforgivably slow I was for someone with an interest in First World War aircraft and how annoyed and embarrassed I should now be. I related this to my companion after the credits. "Yes," he said. "I could tell all that from the noise you made."
P.S: I am drinking tequila and grapefruit juice with a spoonful of sugar, and it's awfully nice. What do you suppose I should call it?