Gerard Stembridge writes novels and screenplays and is a theatre and film director.

His 2011 novel Unspoken worked through the story of Ireland in the 1960s as observed by both real and imagined characters.

The Effect Of Her replicates this for Ireland in the 1970s and, different decades notwithstanding, the two novels are remarkably similar. They are almost identical in length and narrated by so many shifting voices that the reader needs a mind-map to keep track of them all. Both introduce multiple story lines, many of which end up searching for somewhere to go.

The most promising storyline in The Effect Of Her is that of Fianna Fáil politician 'CJ' (a not-even-thinly disguised Charles Haughey), his mistress Terry and his brooding adviser Michael Liston. CJ is in the political doldrums as a result of alleged involvement in gun running to Northern Ireland but Liston has a plan to put wind in his sails.

The adviser has problems of his own, however, in the form of his girlfriend Mags, who is campaigning to legalise contraception, and his son Matthew, who is in trouble at his Christian Brothers school.

So far, so good: the characters are nicely drawn and their interactions are alive with possibility. Terry and Mags are intelligent and articulate women who test male-dominated Irish society and stiffen their resistance when church and state push back. CJ is a scruples-free political operator who needs new friends and money to fuel a political comeback and Liston's attitudes to the issues of the day are determined entirely by how his boss's fortunes are affected.

Stembridge's exploration of the relationship between politician and adviser is first rate. CJ's factory setting is a kind of weasel-attentiveness and he is fired by an insatiable hunger for power. Here he eats a rack of lamb while Liston explains the advantages of holding offshore funds in the Cayman Islands: "CJ let Liston talk while he sliced and ate, sliced and ate, chewing, chewing, chewing, the better to relish the youthful sweetness of the lamb's blood. Once he'd stripped the swollen eye of flesh from each cutlet, he snatched up the little pink-flecked bone and sucked and gnawed."

Unfortunately, the potential in CJ, Liston and their female partners is not fulfilled. The middle third of the novel is handed over to a variety of tedious teenage voices, some of them from the next generation of families first introduced in Unspoken.

A chapter dedicated to describing the scene at a local disco has no purpose other than to show how awkward teenagers can be in each other's company.

CJ and his tangled affairs take a back seat while the teenagers ramble on and other well-known public figures from 1970s Ireland make guest appearances. Fine Gael politician Garret FitzGerald, for instance, gets a few pages to explore the mystery of why he is so sympathetic to women's issues while women remain stubbornly unsympathetic to him.

The novel rights itself in the last few chapters as the number of competing voices diminishes, but that is not enough to quell a feeling of lost promise.

The only strand that has any kind of resolution is that of three gay characters (in various stages of self-awareness) who finally meet up. Everything else is left hanging, which suggests an 1980s sequel to come.

There is certainly more potential in Haughey, who went on to be Taoiseach of Ireland three times and have his 27-year affair with journalist Terry Keane exposed by her on late-night television.

A good editor with a big red pen should make that a story to look forward to.