In the not quite two years since Annie Baker’s The Flick crossed the Atlantic to the National Theatre, “slow theatre” has become a Thing. Unlike other simple-sounding labels, however (“poor theatre”, “holy theatre”), slow theatre is exactly what it sounds like. The drama is not forced or contrived, but unfolds wisp by wisp over as long as it takes and in whatever order it feels like. “As long as it takes” is, in this case, just over three and a quarter hours (including two intervals, with a front-cloth monologue in one), and “whatever order it feels like” includes a deceptive ending, with the play’s title being semi-explained in its very last words, although we have all inferred it ages earlier.

If your relationship is on sticky ground, the obvious place to take your girlfriend on a make-up weekend is Gettysburg, Pennsylvania, to tour the site of the Civil War battle that (ah-ha) determined the fate of the Union. Tom Mothersdale’s Elias isn’t the most sensitive bloom in the bunch; his (partly justified) insecurity manifests in corrosive passive-aggression towards Anneika Rose’s Jenny, whose tether is long but not infinite, strong but not unbreakable. Mertis, the landlady of their über-kitschy B&B, is in Marylouise Burke’s wonderful performance annoying yet compelling, banal and otherworldly, insightful and away with the fairies. Not just the fairies: all kinds of flavours of the numinous, metaphysical, supernatural and eerie crop up almost at random. Mertis considerately reads to a blind friend (who herself is a rum cove) from what we come to realise is one of H.P. Lovecraft’s Cthulhu tales. These things all amount to particles of Philip Pullmanesque “dust”, which we want to believe influences our human actions and relationships but which may simply be floating in the atmosphere.

Director James Macdonald and designer Chloe Lamford enjoy piling up the detailed contradictions and/or pointlessnesses. Burke manually advances the hands of a grandfather clock between scenes, and tops and tails each act by diffidently dragging the curtains across the stage. The decor ranges from a funny/scary pianola to the most tasteless cream-jug outside the pages of P.G. Wodehouse. Like an old Magic Eye picture, if you peer hard enough at it, or past it, the “true” image emerges... or you tell yourself that it does.

Written for the Financial Times.