A young aspiring wildlife photographer is trying out for an apprenticeship with one of the best in the business. Marcus (Charlie Beck) has just arrived at a bird hide, in the middle of nowhere. “No one can hear you scream around here,” says the older man, Tim (Gerard Horan), whose barking grumpiness carries its own threat.

Marcus, under his tutelage, gives as good as he gets and they rub along awkwardly until, slowly, they find affinities: they both hail from the same downtrodden housing estate and there are shadows lurking around their family life. You wonder where this meeting will go, with ambivalence around both men’s behaviour. Does Tim have an ulterior motive in getting Marcus to this remote spot? Is Marcus really who he says he is?

David Pearson’s play reveals its intentions slowly. Directed by Alice Hamilton, it is quietly sensitive and gently paced, although its narrative arc is not quite as full or dramatic as it might be. It is nonetheless filled with keen, tender and funny writing with an affectionate emotional undertow built between the men.

Marcus once took a remarkable picture of a fish eagle, at the seaside, which has earned him a place at this hide. The conversations about photography are engaging and intelligent, from the moral obligations photographers have in extreme situations of suffering (for humans as well as animals) to the notion of a picture’s “truth”.

The title refers to a rare Siberian bird that has never before been photographed outside its Russian habitat, and points to the contested authenticity of a photograph that Tim claims to have taken in Britain (“They say it’s a fake,” he says, smartingly). There are snide, sideways glances at the way iPhones and AI have debased the artform too, which could have been more fully developed.

In the end, the play is as much about fathers and sons as it is about creativity or mentorship. Both men have complicated relationships with their fathers. The structure of the play enacts one of these, and not the other, with a too neat ending, but there is a richness of subject matter and gripping performances. Again and again, this theatre’s downstairs space for emerging writers has revealed talent in the making. This is yet another.

• At Hampstead theatre, London, until 23 May