Kyle Soller, Paul Hilton and John Benjamin Hickey  in The Inheritance
Kyle Soller, Paul Hilton and John Benjamin Hickey in The Inheritance
© Simon Annand

Matthew Lopez's seven-hour epic about gay relationships is destined to be called the new Angels in America, for the generation that came after the AIDS crisis but must grapple with its legacy. But the text it's really in dialogue with is EM Forster's Howards End.

It starts with a corny chorus scene of affected young men looking to the figure of Forster for inspiration when writing their own stories. But from this oddly shaky opening, The Inheritance rapidly grows into a vastly enjoyable, properly gripping, frequently moving piece of event theatre, directed by Stephen Daldry so that you see, crystal clear, a myriad of neat telling details as well as its grand historical sweep.

Despite centering on an interlocking sextet of gay men, Lopez somehow manages to stick remarkably close to the plotting and themes of Howards End. Here too we have battles between liberal idealism and conservative individualism. Property is always more than bricks and mortar – it may confer sanctuary, or stability. It can hold old ghosts and new promises.

But this is a super-smart, not slavish, retelling: Lopez often splits characters or characteristics, finding modern parallels or rewriting their fate, even adding new mirrorings down the generations. This is one of the reasons why The Inheritance needs to be seven hours long: Forster's plot is wildly improbable, but somehow you go with it. Here, the space and time helps these characters feel real, so you follow them through all the juicily unlikely and yet terrifically satisfying coincidences and reversals in fortune. That said, I do wonder if it works so well if you're not playing map-the-plot in your head…

But I suspect it does. For The Inheritance has an almost soapy addictiveness all of its own, like a Netflix binge where you keep putting on one more episode. It also has the depth of characterisation of a novel – maybe 'depth' is the wrong word, maybe it's more durational than that: you feel you have lived with these people.

Could it have been a novel or a TV series? Yup. But I wouldn't wish it out of the theatre for a minute. Because this is such a hugely absorbing experience. Lopez and Daldry both manage the pace superbly; it's a cliche to promise the time will fly by, but it will.

Much of the cast spend the whole thing on stage – a bare, grey platform that goes up and down a bit. Occasionally a doll's house or small tree appears at the back; both are twee, needless additions frankly. But the cast's constant presence reflects how this is a community trying to find their story. In the first half, this notion is more explicit, the men interrupting each other with rewrites, the hovering Forster pushing them to find their truth – before being taken to task for never making it out of the closet himself.

The cast are impressive, especially the ever-vivid Kyle Soller, who imbues our understated hero Eric with tremendous warmth and generosity of spirit as he tries to work out how to make a life count. The other stand-out is Andrew Burnap as his narcissistic, fabulously vain playwright lover Toby, an irresistible nightmare dripping both charisma and scorn. There's also a late appearance from Vanessa Redgrave, turning what seems almost a glib intertextual reference to the Merchant Ivory film into something strangely, sadly luminous.

There's some cracking writing here: a monologue about a Prague bathhouse that nails the switch from erotic ecstasy to shame; a ding-dong between a Republican property developer and a young radical that flashes as its arguments switchblade; a hilariously camp, champagne-flinging wedding bust-up. There's also some ropey writing, to be honest: Lopez too often tells rather than shows, and falls back on hackneyed phrases. A wince-inducing debate about what it means to be gay today is written like so many bullet points, and there are dollops of schmaltzy sentimentality.

But, oh, you forgive all that… because The Inheritance sweeps you up completely. You root for these characters as individuals, but their stories interlock with each other – and with the past – to form something like an embrace. It feels all-enveloping, and deeply generous.

The Inheritance runs at the Young Vic until 19 May.