Little Eagles doesn't compromise in setting its scene: the play opens with a long speech from Stalin, and his influence hangs over every character for the rest of the play. Director Nicholas Hulbert has chillingly conjured up a country built on fear. Each of the characters is revealed to have betrayed the others to survive; each character joins in the desperate refrain of asking for an apartment of their own. At times it can be bitterly funny, as when the imprisoned and beaten Korolyov declaims some extravagant Stalinist rhetoric in order to get approval for his space programme, but the tension is never fully relaxed.

The grubby, taut atmosphere owes a lot to the production's inspired set design. Snow at a gulag in Kolyma is illustrated not with artificial flakes but dirty white sheets flung over rickety tables; a space rocket is shown by just one of its vast tail fins filling a corner of the stage. It's simple, well-thought-out, and utterly convincing. The careful use of voiceovers is also moving – for once, not merely distracting – as a well-balanced combination of Russian songs and radio recordings is played against the astronauts' communications. If there is the odd hiccup, such as the tiny model spaceship squeaking horribly as it's winched up over the audience, it all somehow plays into the shabby, early 1960s aesthetic. Robbie Aird is powerful as Korolyov, a stern, dedicated scientist who will not permit any obstacles to affect him – from budget issues to imprisonment in a gulag. Although the cast as a whole is strong, Aird really meets his match in Saul Boyer as Kruschev, who brilliantly achieves a tone of jovial psychopathy.

The problem with Little Eagles is that it's just too long. Staging a show lengthy enough to have an interval is always a risk around the infamous Week Five, and the script simply doesn't maintain enough direction or impetus. Even the staging seems to start getting tired in the second half: actors stand in polite lines and speed through their lines as quickly as possible. Perhaps the issue is that this play tries to tell too many stories. There's the struggle of Korolyov to complete his work, against various enemies; the struggle of all the characters to survive under Soviet rule; the journey of the astronauts, the terrible decisions of the doctor, the fate of Korolyov's daughter... Despite the fact that each of these story arcs is acted very convincingly, it might have been better if the script focussed on just one or two.

However, the story of the USSR space programme is undeniably a powerful one, with triumphs, disasters, near-misses and years of work. This production does an excellent job of conveying the Russian atmosphere, and the characters are gripping. As the play teaches us, wonderful things can be achieved with enough time. If only they hadn't taken quite so long.