Then Helen lands a case to investigate. Her slimy ex-boyfriend Jay pops up to ask her to track down Wayne Diffney, the missing member of boy band Laddz, so they can get back together for a lucrative series of reunion gigs. The trouble is, Wayne seems to have disappeared off the face of the Earth and Helen, who has few leads, spends most of her investigation time lying on the floor of his house.
There's no doubt that the descriptions of Helen's depression are authentic and largely based on Keyes' own experience. "I felt like I'd been poisoned," she writes. "Like my brain was squirting out dirty brown toxins, polluting everything."
Yes, it's very dark as Helen recounts her suicide attempts and her stay in a psychiatric ward; her struggle to find "anti-mad pills" that work, the mess and pain inside her head. There are sections where it feels as if Keyes is talking directly to the reader, trying to make us understand her sickness, and as you read it's difficult to put the author aside completely - which isn't ideal in any sort of fiction.
The saving grace is that, while Keyes may feel as if she's been losing her mind over the past few years, she hasn't lost her trademark humour. Somehow she's managed to make a novel about depression as hilarious as it is meaningful. Although the mystery that's central to the plot isn't especially energising - and the love story only a side dish, Helen Walsh's voice is funny, vulnerable and real.
Fans of Keyes, and there are millions of them, may not pick The Mystery Of Mercy Close as their favourite of her novels but I'm willing to bet they won't be disappointed by it either. And while sufferers of depression won't find any answers here, they will be rewarded by an entertaining story that accurately and originally describes the way they feel.