The Cassandra complex by Holly Smale

Cassandra Penelope Dankworth is a creature of habit. She likes what she likes (museums, jumpsuits, her boyfriend Will) and strongly dislikes what she doesn’t (mess, change, her boss drinking out of her mug). Her life runs in a pleasing, predictable order. Until now. She’s just been dumped. She’s just been fired. Her local caf? has run out of banana muffins. Then, something truly unexpected happens: Cassie discovers she can go back and change the past. Now, Cassie should be able to find a way to fix the life she accidentally obliterated. And with time on her side, how hard can it be?