“You can’t arrest the internet,” exclaims the bereaved father in this superb Tony-winning musical. The primary meaning of his words is that you can’t apprehend it as if it were a criminal. But the secondary meaning has here become the primary one: you can’t stop dead a phenomenon that is as weightless as the ether, and yet can crush individual lives like a conscienceless juggernaut.

Steven Levenson’s script is unflaggingly wily and kicks off from a very intriguing premise. It focuses on a socially awkward teenage boy (the eponymous Evan, played by Sam Tutty) who, at the suggestion of his shrink, tries to raise his spirits each day by sending himself a pep talk email.

One of these fanciful missives is found in the pocket of a fellow student, Connor Murphy (Doug Colling), after his death by suicide. The only contact the two ever had was when the disaffected Connor scrawled his name on the plaster cast that Evan is wearing because he has a broken arm from falling out of a tree. The circumstances of this “fall”, which seem initially idiotic, are shown to be more significant as the piece develops. Connor’s stricken family reach out and befriend Evan, who does not start off with the intention of deceiving them, but ends up doing so anyway.

David Korins’s scenic design (with projection design by Peter Nigrini) consists of tall, wafer-thin sliding screens. Each of them displays a stacked column of computer screens. These in turn convey the unceasing traffic of social media activity. The moral indifference of this wired-up world is contrasted with the human damage of persuading people that they are worthless unless they have gained access to the fickle illusion of being surrounded by “friends”.

The wonderful score, written by the vastly talented songwriting team of Benj Pasek and Justin Paul, communicates the anxiety of this – particularly the one-note pulse nagging under the early song, “Waving Through A Window”. It’s sung by the nerdy protagonist, who twitches and flinches and yearns with such a low sense of entitlement he’d make Kafka look bumptious.