Timothée Chalamet and Eileen Atkins were fully rehearsed for this family drama at London’s Old Vic when theatres closed due to Covid in 2020. After its eventual cancellation, Atkins picks up her role as 91-year-old Greenwich Village lefty Vera, directed instead by Richard Eyre in Chichester, opposite Heartstopper’s Sebastian Croft in lieu of Chalamet. Croft plays Vera’s 21-year-old grandson, Leo, who arrives out of the blue after a cross-country bike ride. Leo has hauled plenty of baggage with him, which is unpacked over several weeks. Amy Herzog’s 2011 play (a Pulitzer finalist) may have the familiar premise of odd couple flatmates but is distinguished by their startling topics of conversation: the amount of tongue, for example, used in Leo’s recent kiss with his adopted sister, or how his girlfriend Bec has “kind of a weird pussy”. 4000 Miles is less uproarious than that may suggest as, in an interval-free hour and a half, it explores communication both thwarted and hard won. Sometimes the battle is with oneself: Atkins brings rage and fear to Vera’s refrain “whaddayacallit?” when words fail her. Elsewhere the point is made more obviously through a glitchy Skype call between siblings. But Herzog achieves rich tragicomedy when Leo’s longest heartfelt speech is mostly missed by Vera, who doesn’t have her hearing aid in. Atkins is wonderful as the nonagenarian with no filter – her irritability accompanied by exquisite flicks of the wrist, her tenderness emerging through gestures rather than speeches. Croft conveys the stalling effects of trauma beneath Leo’s snappy chatter but there is an emotional distance and increasing heaviness in the production, which punctuates scenes with often solemn, contemplative music and never fully illuminates the smaller gestures and wispy strangeness of the play. You wish Herzog delved deeper, too, into the differing shades of leftist thinking between Leo and his grandmother, whose apartment pointedly hasn’t been redecorated since the turbulence of 1968. The contrast is partially explored with the arrival of Bec (Nell Barlow), but it is only when Leo hooks up one night with Chinese-American student Amanda (Elizabeth Chu) that Vera’s politics finally propel a scene. Her books on communism dampen the mood for Amanda more than Vera herself emerging bleary-eyed in her nightdress on Peter McKintosh’s artfully cluttered set. The play never leaves these four walls, even though it is very much about the journey not the destination, but there is greater mileage yet that could be found in its wistful tale of relationships gained, lost and gently rekindled. At Minerva theatre, Chichester, until 10 June