Guy Stockdale, a 62-year-old judge in an English town, has made a decision. When he gets home he will finally tell his wife about the seven-year affair he has been having with a barrister half his age. He will leave Laura and their rambling rural home to make a new start with the love of his life, Merrion. He will turn his back on over 30 years of marriage and set about marrying the mistress.
The effects of this bombshell on Guy's family are explored by best-selling British author, Joanna Trollope, in an undemanding read that lives up to everything her (mostly female) fan-base has come to expect. This is a book about relationships and how unexpected events - your father running off with a leggy thirty-something, say, can alter the dynamic of a family forever.
Simon Stockdale, Guy and Laura's grown-up son, feels deeply obligated to his mother but is not sure he can survive the constant demands she places on him after the split. Carrie, his wife, is positive their marriage can't. Their teenage children (Trollope falls down here, the language and behaviour she attributes to the younger generation are at times embarrassingly off the mark) simply play their music very loud and try to escape the mess.
Although Guy is the cause of the turmoil, he cuts a far more sympathetic figure than the gardening-obsessed Laura who, it emerges, refused to acknowledge the gulf that slowly widened between the couple over the years: she was too busy planting borders. And then there is Merrion, "a proper person" as Guy's other son Alan remarks, and Merrion's mother, who can't bear to see her daughter throwing her life away.
Those for whom family minutiae hold no fascination will doubtless find Marrying the Mistress terminally dull. For those who eagerly wait to get stuck into a new Trollope, the eye for domestic detail and the subtleties of human behaviour displayed here will not disappoint.
Roisin Ingle is an Irish Times journalist