Ruth Leon was married to Sheridan Morley - theatre critic, broadcaster and Britain's pre-eminent arts journalist. He'd suffered from bouts of depression all his life but suddenly, after a mild stroke, his usual treatments stopped working. He sat, crying, his chin pressed down into his chest, all day, every day. Ruth looked after him - sometimes gracefully and sympathetically, often angrily and tensely. Also an arts journalist, for two years she did her own freelance work as well as his. She no longer recognised her husband, but she could be him.

One day, a consultant in Oxford said he thought they'd been treating the wrong kind of depression; that the stroke had damaged the emotional centre of Sheridan's brain. He knew of a procedure that might help, but it had never before been performed in the UK. It was an outlandish, fantastical idea - an implant would be put in Sheridan's brain that would allow doctors to adjust his mood with an electronic remote control. They would be tampering with the very core of what made Sheridan Sheridan. On behalf of her long-absent husband, Ruth agreed.

Ruth Leon's account of this unique journey to the heart of what it is to be human is as honest and moving as it is fascinating and challenging.