The ascendance of Suranne Jones from Coronation Street star to a creative force to be reckoned with over the last couple of decades has provided food for the soul as well as a feast of entertainment. Now the indefatigable Jones returns to the small screen (between the last series of Gentleman Jack and the second series of Vigil, arriving shortly) in the new ITV drama Maryland, directed by another former soap star, Susan Tully (Michelle Fowler, from the days when EastEnders was great in every way). Jones, who co-created Maryland with writer Anne Marie O’Connor, co-stars with Eve Best, who is one of the many faces here (Hugh Quarshie and Dean Lennox Kelly foremost among them) who make you cry: “Oh my God – yes! Why is this person not on my television more?!”

Maryland opens like a thriller, with a dead body discovered on a lonely stretch of beach on the Isle of Man and, soon after that, a woman taking delivery of a large package of smuggled drugs. This is a slightly unfortunate misdirection because it is not a thriller at all, but a chamber piece about family dynamics, female identity and ways of finding freedom before it is too late. The period of expectation-adjustment is a waste, but once get your eye in, it is a joy.

The body is that of Mary, the mother of Becca (Jones) and Rosaline (Best). They thought she was on holiday in Wales with her friend Maureen and are baffled as well as grief-stricken when they are given the news and have to fly to the island to begin the repatriation process. The sisters have grown apart over the years, as often happens with siblings. This is partly because they have gone down different paths: Becca married young and is now in the thick of family life with two teenagers and Rosaline is devoted to her career, though she keeps a toyboy around who is happy to be called on in her moments of leisure. It is also partly because of their childhood history, which is gradually revealed, and the effects that traumatic events can have. Again, it is not a thriller; we are talking about ordinary trauma, not murder or kidnapping or anything. But it is all the more affecting for that, as is the fact that the sisters clearly still love each other and that – like all of us – they have accreted stuff between them that needs clearing away.

Their mother’s death acts as a catalyst for, and a distraction from, such an undertaking, as they come to realise that Mary had been leading a double life for years. Unbeknownst to her children, Mary was adopted. She tracked down her biological mother to the Isle of Man and so began her secret visits there. When Mary’s mother died, she left her the house – which now passes to the girls – to be held in trust down the generations “for the betterment of the women in the family”. It is filled with pictures of the girls growing up and of Mary with her circle of friends in the community. They include a lover, the elegant, erudite Peter (Quarshie), who could not be more different from her decidedly inelegant and inerudite husband (and the girls’ father) Richard (George Costigan) back home, and Cathy – the woman we first saw thanking a man in a rowing boat for bringing her a boatful of marijuana. Cathy is played by Stockard Channing, who is a great actor but her wild energy is barely contained here and unbalances her scenes: it feels a bit like Elizabeth Taylor walking into a Rattigan play.

Maryland’s greatest strength lies in the scenes between the sisters, as they bicker, laugh, cry, barrel through the revelations together in front of people, then fall apart when they are alone. Past and present tensions rise and fall, and their increasingly truthful and bitter arguments are beautifully written and performed – right down to the silences that succeed them. Because after you have said that day’s piece, what are you going to do? Stop being sisters? Never speak again? It is not that kind of drama, it is not that kind of relationship, it is not that kind of history. Maryland confounds your expectations and is all the better, all the more credible and all the more moving for it.