König Lear, silly old fool that he was, decided prematurely to divide his property among his children, and thereby unleashed almighty havoc into the world. His darker purpose, “badly conceived”, was simple enough: to make sure there was someone look after him in his old age (soliciting no small amount of flattery along the way.) Of course, it all backfired spectacularly on him – and Manfred, the scientist father of Meike, can demonstrate why. Working with flipchart and marker, he details the formula which governs the relationship between emissions (property) and impulses (love). It's simple really: Lear jumped the gun.

In Testament, four members of German theatre company She She Pop have persuaded three of their real, live fathers (the fourth is defined both here and in his daughter's life by his absence) to join them first in the rehearsal space and then on stage to cast a cold eye on filial obligations by way of King Lear. The presence of non-actors on stage means we are in different territory from the off, and all expectations should be carefully adjusted. This is not an emotional journey through which we will get to know the fathers and their daughters – the men resist this outright. Rather it is an investigation by the company into the tough questions that lie ahead as their fathers slip slowly through the last of the seven ages, an investigative process which is here re-presented for us in a fun, uncomplicated and honest way.

A trumpet heralds the arrival of each old king on stage. With daughters in ruffs and fathers in riding boots, the men are applauded onto the stage in chat-show style, to take up their positions in three armchairs house left, each facing into a camera which projects his face, in soft focus, onto one of three large portrait frames which hang against stylised wallpaper. The text of King Lear itself, pinned to a flipchart, is projected onto a large screen to the right, with edits and notes clearly marked. There are headphones for playing back earlier rehearsals. The process is thus laid bare on stage, and it is replayed with humour and precision.

Structured around the five acts of Shakespeare's tragedy, the company's findings are quite unforgiving. There may be no kingdom to share out, but the stakes are high nevertheless: there is the question of inheritance – what do our fathers owe us? (There is no way that Peter, father of Fanni, is going to surrender his Lichtenstein print.) On whose terms are we willing to have our fathers come live with us? (Lisa uses magnetic strips to demonstrate how her father's bookshelves cannot possibly fit into her hypothetical 150 sq metre apartment.) How will the men hold on to respect after retirement? (Power-tools seem key.) How will the daughters cope with their fathers' physical degeneration and increasing needs? (Theo, father of Ilia, states that it is not the 100 knights but the 100 handicaps that his daughter will find hard to accommodate.) What can we forgive of fathers, and they of their daughters? And how do our fathers want to be remembered when they are gone?

At its tempestuous centre, Testament is about how relationships with our fathers must be renegotiated as we move towards and then beyond that pivotal point when the roles of carer and cared for are swapped – here this changeover takes place during the storm scene in Act III, when to a pumped up soundtrack we see the daughters divest their fathers of their boots and breeches, and usurp their thrones in cardboard crowns, whooping all the while. We watch as the three men reduced to their underwear, ageing bodies exposed, rally their efforts to reclaim the text from their daughters and their dignity in the face of age; a shaking hand scrolls back through Lear to outline in red pen the passage which must not be overlooked. It's a strong and moving image in a production which otherwise eschews the provoking of strong emotions – much as the fair Cordelia might refuse to be manipulated into such declarations.

In bringing their real fathers on stage in Testament, She She Pop is striving to get beyond artifice and illusion to reach something true – but the ultimate gesture is made by their fathers, who are not actors after all, yet are willing to do this for their daughters. Surely an emission (gift) that should trigger the appropriate impulse (love).

Fíona Ní Chinnéide is Reviews Editor of Irish Theatre Magazine