Theatre review: A Slow Fire

Simon Stephens has had shows open in major West End houses but his latest gets its UK premiere in one of the most intimate spaces in the middle of Theatreland: Written for Irish theatre company Glass Mask, A Slow Fire transfers to Jermyn Street, a venue famous for having to make such inventive use of a small space that the audience has to cross the stage to get to the toilets. And a cramped space is appropriate for a story set in a nuclear bunker: Ashton (Ross Gaynor) and Reece (Ian Toner) share a space built by the former, once a theology lecturer at the university where the latter was a porter. How they ended up in there together is down to pure chance as much as anything, but they've managed for three years now since the unnamed apocalyptic event that seems to have killed most of the population.The world outside isn't entirely out of bounds to them: Occasionally they feel safe enough to go outside, see what's changed - people seem to be stealing the railway tracks for some…