Welsh dance company Earthfall has taken the central relationship from Jamie O’Neill’s award-winning novel At Swim Two Boys and turned it into a riveting, hour-long rhapsody of developing love between two young Irish men, Jim Mack and Doyler Doyle.

In the novel (and we could have done with an explanation of this in the programme), the boys make a pact: Doyler will teach Jim to swim, and in a year, on Easter Sunday, 1916, they will swim to the distant island of Muglin’s Rock and claim it for themselves.

The whole work takes place on a flooded stage, with a waterfall tinkling on to the pool below. At the start, the attraction between the two is palpable, but although irresistibly drawn to each other, they seem inhibited by guilty feelings and uncertainty. The choreography is remarkable; the two boys lift each other in increasingly complex, intertwined positions, they leap over each other in the shallow water of the stage, and most strikingly, they slide and swirl in great sweeping glides across the floor, with water showering around them.

What we are watching is a gradually developing intimacy, an attraction that eventually can’t be denied any longer. Finally they complete the swim. Doyler almost drowns, but Jim saves him, and it is now that they kiss for the first time. But this is a love story that ends in tragedy. It’s set during the period of the First World War, and Easter Sunday, 1916, is the day of the Easter Rising in Ireland.

During the fighting Doyler is shot and dies in Jim’s arms. This is a very poignant piece, with what’s really physical theatre entering into the realms of dance, though Daniel Connor and Murilo D’Imperio Leite are clearly trained dancers. Leite diminutive, gentle and appealing, Connor powerful and brave, dancing with an unconscious nobility. There can’t have been anyone in the full house who was not moved by this work.

At Swim Two Boys is at The Riverside Studios in London from February 7 to 25. Box office: 020 8237 1111.