An unknown stage play by Ted Hughes, The Story of Vasco, will be performed for the first time next month, after its director reconstituted the script from abandoned notes among the poet's papers.

The former poet laureate, who died in 1998, was commissioned by Sadler's Wells in 1965 to adapt a Georges Schehadé play as a libretto. Sections of his work were used in an opera by Gordon Crosse which opened in 1974, but the complete text of Hughes's translation lay unremarked in a couple of folders marked "Vasco" in the archives of Emory University in Atlanta Georgia.

The director Adam Barnard had come across a prose translation of Schehadé's play in a secondhand bookshop and was trying to find out more about it in the British Library when he read that Crosse described the libretto as being drawn from a verse translation, with the resulting text being about half-pure Hughes.

"My question then became, does the pure Hughes text survive," he said. With no trace in the British Library, Barnard got in touch with the archive in Atlanta, who sent over a list of what was in their collection.

"We got this huge index of the archive," said Barnard, "with these two mysterious folders marked 'Vasco' in box 114".

It was a "huge eureka moment", he continued, but also extremely frustrating. "You see the title there, but you can't see the folders, because they're on the other side of the Atlantic."

Emory sent over images of every piece of paper within these folders, including pages relating to a children's poetry competition Hughes had been judging, which Barnard gradually assembled into a series of drafts and rewrites written over a period of two years while Hughes was fulfilling the commission.

The play tells the story of a fainthearted barber who is persuaded to undertake a dangerous mission in the war, which has defeated even the bravest heroes. Only a man who has no idea of the danger he runs may have a chance, so the barber is catapulted into the most perilous zones, pursued by a peasant daughter who dreams of a scissor-wielding hero.

"It's a very remarkable and unusual piece of theatre," Barnard said. "There's a lot of imagery in Schehadé's prose. Hughes just takes that and runs with it." Nature imagery and visual motifs typical of Hughes recur throughout the play, with crows appearing as harbingers of war. Hughes was to publish his breakthrough collection, Crow, just three years after delivering his contribution in 1970.

Despite the play's striking imagery and granite rhythm, according to Barnard it's a very "actor friendly text".

"One of the things we're finding in rehearsal is that Hughes really understands what makes a scene tick," he said. "He has an impressive dramatic economy."

The Story of Vasco runs at the Orange Tree Theatre in Richmond from 25 March to 25 April.