Radcliffe Square – it’s one of the world’s most beautiful sights, and has been made even more famous by its frequent appearances in the Lewis TV series. Now it becomes the backdrop for Tightrope, a new show devised by the Under Construction theatre company. It’s a promenade production, which will also have audiences visiting the adjoining University Church and its Vaults Café.

“It’s the idea of walking on the edge, or treading a thin line between safety and danger,” explained Oxford-born artistic director Lizzy McBain. “The idea is that St Mary’s has become a citadel, a sort of enclosed community where people are both protected but also trapped within the walls of the church. It’s drawing on the medieval influences of this building, when it was the heart of the city.”

Could those medieval influences become creepier during the evening, as darkness falls, I wondered.

“There will certainly be a slightly sinister twist. The ghosts of the citadel will emerge in some way or another, for sure. I don’t want to give too much away, but we will be asking the audience to question what it is that they believe in, and stand true to – whether that’s fairy tales, science, or religion. There’ll be aspects of all these subjects in the characters that we see, but there’s one girl who tells a really absurd, and slightly dark story about something that’s happened to her. But no-one believes her.”

Tightrope will also employ the latest stage technology: the Ashmolean has granted the company the right to digitally project Uccello’s The Hunt in the Forest. Exactly how a world-famous square, and an equally world-famous painting meld together will be revealed in performances tomorrow and on Saturday. Start 8pm – tickets on the door, (St Mary’s, Radcliffe Square entrance) or 01865 305305.