Storyline

In an isolated island, a young woman receives letters form someone far away. she lives under the same roof with an older woman. a young postman arrives. a stray dog follows him from the very start. the three characters seem to lead separate lives, with no obvious bond between them. Still, as the story unfolds, the sender's letters seem to interweave the three characters. is it the sender's voice or their own voices they never listened to?