Sixteen films are competing for the festival's main prize, the Golden Lions, with three further competitions for debuts, young-adult cinema and short films.
The opening ceremony, held at Gdynia's Musical Theatre, also marked the 60th anniversary of the Polish Filmmakers Association.
Artistic director Joanna Łapińska said the beginning of the festival's second half-century was a fitting moment to reflect on "the power of culture" and its responsibilities.
She highlighted a programme featuring classic works by the late directors Andrzej Wajda and Krzysztof Kieślowski.
Deputy mayor Oktawia Gorzeńska linked the festival to the city's centenary celebrations, noting that Gdynia's modernist centre was added to the UNESCO World Heritage List this year.
Holoubek's opening film, based on a script written more than a decade ago, is set in a small town in eastern Poland in the winter of 1943.
The arrival of a mysterious German official from Berlin unsettles the community amid rumours of missing gold.
The cast includes Itay Tiran, Joanna Kulig, Robert Więckiewicz and Magdalena Różczka.
The movie had premiered at the Toronto International Film Festival just days earlier.
One of the films in competition is Paweł Pawlikowski's Fatherland (Ojczyzna), his first entry since Ida and Cold War.
The main jury is chaired by director and screenwriter Krzysztof Zanussi.
This year's Platinum Lions lifetime achievement award will go to film editor Halina Prugar-Ketling, whose four-decade career includes collaborations with Wajda, Roman Polański and Jerzy Skolimowski.
The 51st Polish Film Festival in Gdynia runs until Saturday.
(ał)
Source: PAP, polskieradio.pl