‘Out in the garden, sunlight blaring. Ellie lumbering after. Run along you two and don’t get into mischief. The leaves of the apple tree blotching us with shadows. Away from the dark house with the curtains pulled shut. The cushions huddling. The mumbles and sighs that boil up into yells and sobs at the sight of water rings from the bottom of a glass. A manner missed. Not me – it’s always Ellie. Never my fault. I’m the good one because I was born first.’

Helen and Ellie are identical twins. One day they decide to play a game, and they swap places. But Ellie refuses to swap back and Helen finds herself trapped in a nightmare from which she can’t escape. Her clothes, her friends, her good grades at school, her mother’s favour – all are taken from her and given instead to Ellie, who thrives on the attention. As the years pass, Helen loses more and more of herself, until only ‘Smudge’ is left.

I have to admit I wasn’t expecting a great deal when I picked up this book, thinking that it would probably turn out to be little more than an average psychological thriller cashing in on the trend for damaged female characters currently taking over the genre (Gone Girl, The Girl on the Train, etc)…

How wrong I was. Beside Myself is a fantastic novel, a psychological drama so piercingly well written that for a long time afterwards anything else I read seemed bland by comparison. For a debut novel, it is astoundingly confident. Profoundly unsettling and very grim – though not without flashes of beauty and happiness – Morgan has set herself up as an author to be reckoned with.

Morgan delves inside the psychology of her characters, plumbing their depths and coming up with handful after handful of raw emotion. She has captured the torment and turbulent ups-and-downs of mental illness and identity crises without resorting to cliché and without grasping at sympathy.

Morgan’s writing is the real star here. She manages to craft sentences in a way that makes them disjointed yet poignant, bleak yet hopeful. Even events that have become familiar in novels are written in such a way as to make them seem entirely new and original.

Morgan does particularly well at capturing the voices of children. The early chapters when Helen and Ellie are young are written in a convincingly childish voice but this never becomes annoying or unrealistic.

The only flaw I found was that occasionally some scenes were a little over the top, but this is a small complaint. Some might find parts of the book confusing or disjointed, or else too dark for their taste, but I thought the desperate, hectic style of some of the chapters only added to the story and helped to create a more realistic view of the characters.

As I read I was a little worried about how it was going to end, thinking it would either be very sudden and bleak or else saccharine sweet, but once again Morgan defied my expectations and balanced on a knife edge between the two, crafting an utterly satisfying reading experience.

I would highly recommend this book, and I know I will be keeping an eager eye out for more from this author in the future. An intense study of family and identity, this is a book you won’t forget in a hurry.

Thanks very much to Bloomsbury for a copy of this book in exchange for an honest review.