The worlds of the haves and the have-nots clash, in a toxic friendship between two women brought together by a school reunionOf all the seven deadly sins, envy is the last to be commodified. You can understand why – unlike lust, anger or even sloth, it’s not something to admit to. In his Allegory with Venus and Cupid, Bronzino depicted envy as an ugly green hag, clutching her head and howling impotently; now Instagram has allowed anyone online to gain access to images of the lifestyles of those richer, prettier and luckier than ourselves.Ruth, the narrator of Harriet Lane’s third novel, Other People’s Fun, is corroded by it. Alone, her marriage over, her daughter grown and her freelance work as dull as it is low paid, she is that most dangerous of characters: an overlooked middle-aged woman with nothing to lose. When she bumps into beautiful, stupid and entitled Sookie at a school reunion, she reconnects with her teenage self “and all her violent desires”. Having flown und...