Celestine is a little mouse trying to avoid a dental career while Ernest is a big bear craving an artistic outlet. When Celestine meets Ernest, they overcome their natural enmity by forging a life of crime together.

Rome, Paris and Helsinki right after the Madrid bombings. Three stories about people who, for different reasons, are afraid of others – the eponymous "thy neighbor." A humanity full of differences, but at the same time, with very similar feelings. So similar that their stories appear almost parallel and complementary.

The dream of Charles Dombais, the wealthy owner of the shipping company, is to have a son to continue his business. Tragically, his wife dies shortly after giving birth to their son.