I 1950'ernes Moskva begynder kommunisten Katya (Rebecca Ferguson) at spionere for amerikanerne. Hendes job er at lokke hemmeligheder ud af embedsmanden Alexander (Sam Reid), men undervejs bliver hun forelsket i ham. 40 år senere møder vi pigen Lauren (også Rebecca Ferguson), og vi møder en ældre Alexander (nu spillet af Charles Dance). Hvad skete der egentlig med hans forhold til Katya for mange år siden? Og hvad er Laurens forbindelse til Alexander?

Den 15. november 2017 blev maleriet »Salvator mundi«, der tilskrives den italienske kunstner Leonardo da Vinci (1452-1519), solgt for en hidtil uset pris på 450 millioner dollars. En undersøgelse af kunstverdenens beskidte hemmeligheder og den overraskende historie om, hvordan et kunstværk er i stand til at forstyrre både personlige og geopolitiske interesser.

A young woman who has just started a job at an art museum writes an email to a friend she lived with until recently. The other woman, also young, works as an artist and has just moved to a new city. A narrator reads this email, but we don't know which of the two women the voice belongs to, whether to the sender or to the receiver of the message. Neither are we aware of the details of this relationship; but what we do know is that, in addition to their interest in art, they share a concern for the difficulties of carrying out their personal and professional lives in the present. By focusing on the peripheral or hidden details of some paintings in the Bilbao Fine Arts Museum, this narrator relates several stories linked to the social, economic and psychological conditions of the artists, both past and present.

A journey through the Spain of the Baroque, the glorious 17th century, an unfortunate era of endless wars and political tribulations; but also of great painters and sculptors who created astonishing pieces of art: el Siglo de Oro.