The Lost Girl by Anne Ursu
Twin sisters Iris and Lark are identical…but not the same. Lark is creative and optimistic and shy. Iris is fierce and loyal and impulsive. But they work together. They always have and they always will. Until they get put into different classes for fifth grade. Iris knows Lark needs her. But she never realized how much she needed Lark. To make matters worse, their parents have decided to enroll them in different after-school programs as well. For the first time in her life, Iris feels separate from Lark. She even starts keeping secrets, like not telling Lark about the giant crow she sees or the fact that she’s been going to a creepy antique store by herself. And this is not a time for keeping secrets…not when things (and even people) are going missing.
Recommended for readers in grades 5 and up who like stories with a little bit of magic, a few cats, and a lot to think about.