Nat has a new job at a local pub; her colleague Neil has worked there for a while. The pub is quiet and, as the two skive off in the storeroom, a spark of attraction begins to flare. But then things get confusing: we see the same conversation again, only this time it’s a little spikier and chillier. Soon we realise we’re watching two intercut narratives – each starting from the same point but heading off in different directions, as Nat and Neil grow either together or apart.

So far, so Sliding Doors, but there’s a crucial difference in Shadows. There’s no outside event to make the two storylines diverge: instead we simply see tiny differences in the way the characters respond to each other, which feed on themselves and magnify over time. In one branch, for example, they enjoy some matey banter; in the other the same conversation is serious and heartfelt. Needless to say, when we revisit them later, the couple who formed the genuine connection are the ones who are doing well.

But what’s actually happening here? Why are we watching two separate timelines side-by-side? If you read the programme blurb, it all falls into place: the ‘bad’ version is reality, while the ‘good’ version is an idealised fantasy which exists only inside Nat’s head. That founding concept needs to be much, much clearer – I confess that I missed it completely as I watched the play, and only picked up on it when I checked the show’s listing later on.

But once you grasp the pattern, some interesting and telling perspectives open up. In the real-world timeline, for example, the couple are divided by education and social class; Nat is unintentionally condescending, while James feels resentful and inferior. James calls that out, yet in Nat’s imagined version of the scene, instead of handling things better she simply edits in a slightly more cultured James. It’s depressing but realistic, and there’s an important moral there – though you have to work quite hard to find it.

The presentation is stylish, with a set made of cupboards and beer kegs, all painted in blank-canvas white. There are some neat projections too, further elaborating Nat’s desire for both love and self-expression. But the downside of such cleanness is that it’s difficult to keep track; there are clever verbal references calling back to earlier conversations, but it’s impossible to remember whether it was fantasy or reality when we heard them before. The opening scene also seems to be out of chronological order – a standard enough framing device, but one which becomes confusing alongside the complex structure of the rest of the play.

Shadows is a smart and thoughtful piece of theatre, which uses the familiar-seeming trope we know from Sliding Doors but explores it in a new and rewarding way. Perhaps it over-estimates our ability to follow along, and you might come out of it asking yourself exactly what it was trying to say. But the ambition is inspiring… and with a little bit more clarity, it has the makings of something meaningful, even groundbreaking.