Out of the blue, a woman walks out on her husband. Bags packed and ready to go, at the last moment she crumples up the letter she has written to him and vanishes from their Madrid flat. So begins this drama featuring not one but three characters disappearing without a trace from their lives; it sounds soap opera-ish, but mostly The Portuguese House unfolds as polite elegant drama, told with such rich novelistic detail it often feels like it’s getting into the minds of the characters.

Manolo Solo gives an excellent performance as the left-behind husband, Fernando, an introspective mild-mannered geography professor. After his wife’s disappearance, Fernando goes on holiday to Portugal, where he meets a gardener called Manuel. When Manuel drops dead of a heart attack, Fernando decides – like his wife – to leave his old life behind; he assumes Manuel’s identity and takes a job as the gardener at a Portuguese country estate. The owner, Amália (Maria de Medeiros), senses that this intellectual man with glasses and a clumsy way with the loppers is not the man she hired, but doesn’t push it – possibly because she is attracted to him.

Like a doorstop paperback, The Portuguese House is an expansive watch, spanning years and going at a gentle pace for nearly two hours. There are more secrets and lies to come – and another person pretending to be someone they are not. That would be a twist too far in another film, but works here in a restrained drama that treats all its characters generously and with sympathy. Though in the end I wondered if it is possibly too respectful, sweeping away difficult hard-to-shift feelings like autumn leaves.

• The Portuguese House is in UK cinemas from 2 October.