What constitutes happiness is constantly being redefined in the pages of novels. In Catherine Deveny's The Happiness Show, Lizzie Quealy is finding contentment hard to pin down. Lizzie is a 38-year-old comedian who lives in Melbourne with her husband, Jim, and their two children. She is rather brash, uninhibited and, as if to confirm these traits, a redhead. Her husband is loving, apparently ''hung like a horse'' and more than happy to take care of the kids. When Lizzie is given the chance to make a show for the BBC, he embraces the opportunity to exit the rat race and ''sit back and be Denis Thatcher''.

On the other side of the world, Tom is similarly ensconced in the humdrum responsibilities of adulthood. A lawyer living in London, Tom is married to Felicity, who first appears ''immaculate in cream linen'' and later lowers herself onto ''the new couch she'd bought at Harrods''. Their middle-class incarnation is perfected by their employment of a housekeeper who arrived in the country as an Iraqi asylum seeker, having lost three generations of her family when ''Saddam Hussein was having a particularly bad day''.

Tom and Lizzie are connected by the romance they once shared. They met on a backpacking holiday on the Trans-Siberian Express in their 20s. Lizzie had flashed her breasts to save Tom's camera from certain theft. Tom had thought Lizzie to be a paragon of all that could be desirable about a woman: ''She was part Tank Girl, part Lara Croft and part Annie Get Your Gun. She was the heroine of her own novel.''

When coincidence leads Lizzie and Tom to meet again years later, their attraction is revived. The former lovers reminisce, conceal the importance of the encounter from their respective spouses and begin to email each other. The tension this creates, the back and forth of wanting but not having, fuels the bulk of the novel.

Sex is prominent. There's the sex Lizzie has with her husband, but mostly there's yearning for what she once had with Tom and longs for again. The subject turns up casually - ''The humidity felt so exotic and so sexy. She felt as if she were with an old lover'' - and more explicitly in the emailed and spoken exchanges between Tom and Lizzie. Whether one of them is wet, or hard, or they ''moved together like a tide'' is frequently addressed. The author's desire to cultivate a brand of raciness for a female demographic is clear, but whether that is achieved is another matter.

Sex and its surrounding territory is notoriously perilous material for writers. Just ask Phillip Roth.

Deveny has often demonstrated her interest in being controversial - a method established in her columns, public appearances and tweets - and this habit prevails in her first novel. It's particularly apparent in the relationship between Lizzie and her best friend, Jules. Their friendship pointedly veers away from customary notions of femininity. In theory, this is appealing, but the effort can go awry. When the ABC passes on Lizzie's pilot at the beginning of the novel, Jules comforts her by observing: ''C---s. I hope their kids get cancer. Got any Tim Tams?'' This is the brand of provocation that Deveny has taught her audience to expect.

The Happiness Show aims to recast an old and well-loved plot about love, lust and longing in a deliberately modern light. It succeeds in being unpredictable within these parameters, but the heavily colloquial and somewhat abrasive voice of its protagonist may be an acquired taste.

THE HAPPINESS SHOW

Catherine Deveny

Black Inc., 288pp, $29.95