Beachy Head, Pleasance, EdinburghThe Interminable Suicide of Gregory Church, Traverse, EdinburghMidsummer (A Play with Songs), Traverse, EdinburghChronicles of Long Kesh, Assembly, Edinburgh

Death permeates the stages of Edinburgh this year, but there's some hope among the doom and gloom

This is Beachy Head, the south coast's notorious suicide spot. A woman named Amy stands on the clifftop, staring over the edge into the darkness. She is struggling to cope with the recent death of her husband, who chose to end it all here.

In fact, Emma Jowett – the pale, thin actress playing Amy – isn't standing still. In this absorbing piece – devised by the young troupe Analogue – she is expressionistically sliding across the stage, clinging to a narrow platform on wheels. It's as if she is reeling from grief. A stagehand is pushing her and – as she leans out to stare down – another cast member suddenly billows her hair back, by swishing a sheet of cardboard.

Beachy Head is most inspired when it's lo-tech. Its live video projections and digitally modified images aren't always so good. The ghost of Amy's spouse, Stephen, (played by Sam Taylor) – implicitly in her mind's eye – appears on the set's rolling screens looking appallingly pixillated. He's a mass of juddering rectangles which is far from atmospheric.

Analogue wants Beachy Head to be objectively scientific in parts. Woven into the plot is an anti-emotional pathologist who, unbelievably, leaves a message on Amy's phone about common injuries sustained, severed feet and so on. Nonetheless, Amy's journey towards letting go of the past becomes, gradually, poignant. And it is tied in with an astute, barbed depiction of two documentary makers who've caught Stephen's suicide on film and persuade themselves that tracking his story and Amy's isn't exploitative.

In terms of recurrent themes, this year's Edinburgh Fringe is strikingly morbid. Not exactly festive. However, the comedian turned storyteller Daniel Kitson's new monologue, The Interminable Suicide of Gregory Church, is a wonderfully idiosyncratic epistolary drama.

Kitson is a weirdie-beardie with pebble glasses and a paunch. Draping his tweed jacket over a rickety pine chair, he relates the strange tale of how he was innocently house-hunting, in an English village, when he discovered an attic stuffed with letters: 30,659 of them to be precise, including the last – seemingly a suicide note – still furled in the ex-inhabitant's dusty typewriter.

Kitson then takes us through his two-year, obsessive-compulsive reading of these carbon-copied reams: his personal mission to rescue the late Mr Church from oblivion.

The Interminable Suicide ... ought to be dreary, but it's gently hilarious and unexpectedly comforting. Kitson relishes quirkily eloquent turns of phrase: twinkling verbal pirouettes about his pathological fondness for glimpsed lives and about hauling himself into the attic in spite of his unmanageable heft.

Furthermore, the first flurry of missives from Church threatening suicide – apparently sent to the local rag, the Inland Revenue, a boy he saw bullied at the bus stop, and others – results in a trove of flamboyantly truculent correspondence and friendships. Kitson creates a remarkably sympathetic biography of a nobody here. A lovely antidote to celebrititis, The Interminable Suicide ... is an ingeniously simple and hopeful piece of work, turning loneliness into communion.

The latest play from writer-director David Greig – entitled Midsummer (A Play with Songs), with a nod to Shakespeare's Dream – is concerned, in turn, about dropping dead. But this is a midlife-crisis romcom with a carpe diem impulse.

Cora Bissett's Helena is a swanky Edinburgh lawyer, who reckons she's only after a one-night stand when she picks up Matthew Pidgeon's Bob, a frustrated criminal lowlifer. They go on a wild bender and both prove more tenderhearted than they think, bridging the class divide and ditching their old lives.

Sometimes Greig's sense of humour feels a mite immature, or like an attempt to be populist, especially when it comes to the caricatured mafia subplot. But it's hard not to be charmed by his two rumbustious actors. Bissett has gorgeous, what-the-hell vivacity. Pidgeon makes whoopie with abandon, when they hurl themselves into bed. And this is a refreshingly alternative musical, too, with the duo stepping out of the action to strum guitars and mellifluously croon nu-folk songs (by co-writer Gordon McIntyre).

On the subject of off-beat musicals, it's also surprisingly entertaining to find shorn-headed political prisoners breaking into a cappella disco hits in Chronicles of Long Kesh, from Northern Ireland. Martin Lynch's play is mainly, and most importantly, a docudrama, moving from the humorous to the harrowing. Based on interviews with ex-inmates and guards (from both sides of the religious divide), it bears witness to what it was like being stuck in the grim Maze Prison during the Troubles and its era of internment without trial.

The cast speeds through the years, boldly mixing verbatim-style authenticity and stylisation, with role-swapping and vigorous mime on a set of battered rostra. In the final scene, brutally beaten-up hunger strikers stagger to their feet and stubbornly chorus one last song from their cells: "All Right Now" by Free; pop turned into a startlingly trenchant protest song.

'Beachy Head' (0131 556 6550) to 30 Aug; 'The Interminable Suicide of Gregory Church' and 'Midsummer' (0131-228 1404) both to 30 Aug; 'Chronicles of Long Kesh' (0131-623 3030) to 30 Aug