With great bravado, 33 year old Helen, the youngest of the Walsh daughters, arrives back home. Not for a visit, but to stay. She had been making a great go of being a private investigator, but when the economy tanked, so did her business and she is now clientless and homeless. With her mortgage in arrears, she is moving back in with mom and dad whether they like it or not, she has a key. Her family is close, but on the dysfunctional side, so she is greeted with a "What are you doing here? We got rid of you."

Things might be slightly better if she moved in with Arty Devlin, her new lover, but that would just be too much commitment on top of this distress. He's a high level cop who does magic with numbers in top secret cases, but his son glowers at her and the beautiful Vonnie, his ex- wife, is too often at his house (just for the kids) and smiles too much.

Then, if that wasn't bad enough, who soon comes calling for her, but none other than her very ex-boyfriend Jay Parker who she thought she had long since washed out of her hair. In her usual snarky way, Helen lets Jay know he is not welcome, but when he offers her double her fee to look for a missing person, the thought of her phone bill and car's need for more petrol raise their little heads and she begrudgingly accepts.

With her oversized black bag, carrying all the stuff she may needs as a PI, Helen is fearless in her determination to find Wayne Diffre. Along with four other members, Wayne had starred as "The Wacky One" in a popular band called the Laddz back in the '90s. Now, with oodles of money to be made on a reunion gig, they desperately needed Wayne to be there. Where could he be?

Helen can be sweet (at times), but more often is sour with a long shovel list of people and things she dislikes (including all music and hot drinks) and would be delighted to smack them all with a big shovel. Yet, she can be joyful with children and has intuitive gifts for making connections which is a boon to her in her role as a PI. Arriving at Wayne's house with a bizarre paint theme (dear to her heart) in a small cul-de-sac called Mercy Close, Helen tries to get a sense of who Wayne is as a person and she likes what she sees. But, the more she investigates, the more she is stymied. Did he leave on his own or was he abducted? With mere days to the highly advertised concert, and a deep depression settling into her mind and bones, will she be able to find him in time for him to go on stage?

Best-selling author Marian Keyes is well known on both sides of the Atlantic and her many fans will be thrilled with her latest release(#5)in the Walsh Sister series. THE MYSTERY OF MERCY CLOSE also reads very well as a stand- alone book for those new to this wonderful Irish author who has a well-deserved reputation as being the Queen of ChickLit.

Drawing on her own experiences and understanding of mental health issues, Keyes skillfully and compassionately integrates into the plot the many challenges Helen faces, not only in trying to solve the case, her dating dilemmas and her feelings in that regard, but also her foreboding sense of a deepening and severe depression and Helen's related suicidal thoughts to stave off that eventuality.