Book about a glass world behind a mirror

Question

There was this book that I read when I was young, maybe like 11 years old. A girl went into the mirror in her bedroom and found this world made entirely of glass. There were glass butterflies and stuff too.

I believe she meets a boy, but there is someone or something that doesn't want her there. The world is also dying/in trouble or something and it's turning black. I don't remember much other than I think a bunny dies, and in the end, a bunch of glass crushes the legs of the boy she's with and she has to abandon him to escape.

Another memory of this that's kind of fuzzy and maybe inaccurate is the girl gets stuck in the world for a while but she is able to see into the world through other mirrors/windows and it seems that a fake version of herself has taken her place back in the real world so her parents don't know she is gone.

If you have any ideas please let me know! It was a pretty heavy theme/story for an 11-year-old and I've been wanting to read it again to see if there's any deeper meanings I missed back then.

Answer 1

This could be one of the books based on the film MirrorMask:

The film's story revolves around a young girl named Helena Campbell, who is sick of her family's career as circus performers. Helena's mother is hospitalized after they have an argument, and Helena finds herself trapped in a fantasy world shortly after.

Helena does not travel to the fantasy land through a mirror - instead,

she wakes up in a dream-like state and leaves her building to find three performers outside. As they try to perform for Helena, a shadow encroaches on the area and two of the performers are consumed by it. The third performer, Valentine (Jason Barry), a juggler, helps to quickly direct Helena to safety through the use of magical flying books.

However, the titular mask could be the mirror element as remembered.

Further,

the City of Light ... is slowly being consumed by shadows

and

Helena discovers that by looking through the windows of the buildings, she can see into her bedroom in the real world, through the drawings of windows that she created and hung on the wall of her room. She discovers that a doppelganger of herself is living there and behaving radically different from her.

Answer 2

It's been ages since I read it, so I might be remembering wrong, but parts of this description remind me of Steven R. Donaldson's Mordant's Need series, a 2 part series that's comprised of The Mirror of Her Dreams and A Man Rides Through. Some parts of the story fit your description, although like I said, it's been forever since I read it, so I'm not sure about the specific details. I do remember the mirrors into other worlds (which is what made me think of this series), and remember that it's excellently written. I also know I fell in love with Donaldson when I was about that age (I discovered Thomas Covenant and was forever hooked). :)

Answer 3

The "Books of Elsewhere" (The Shadows):

Old Ms. McMartin is definitely dead. Now her crumbling Victorian mansion lies vacant. When eleven-year-old Olive and her dippy mathematician parents move in, she knows there's something odd about the place--not least the walls covered in strange antique paintings. But when Olive finds a pair of old spectacles in a dusty drawer, she discovers the most peculiar thing yet: She can travel inside these paintings to a world that's strangely quiet... and eerily like her own. Yet Elsewhere harbors dark secrets--and Morton, an undersized boy with an outsize temper. As she and Morton form an uneasy alliance, Olive finds herself ensnared in a plan darker and more dangerous than she could have imagined, confronting a power that wants to be rid of her by any means necessary. It's up to Olive to save the house from the dark shadows, before the lights go out for good.

Answer 4

Backward Glass by David Lomax.

It's 1977, and Kenny Maxwell is dreading the move away from his friends. But then, behind the walls of his family's new falling-apart Victorian home, he finds something incredible--a mummified baby and a note: "Help me make it not happen, Kenny. Help me stop him."

Shortly afterwards, a beautiful girl named Luka shows up. She introduces Kenny to the backward glass, a mirror that allows them to travel through time. Meeting other "mirror kids" in the past and future is exciting, but there's also danger. The urban legend of Prince Harming, who kidnaps and kills children, is true--and he's hunting them. When Kenny gets stranded in the past, he must find the courage to answer a call for help, change the fate of a baby--and confront his own destiny.

Answer 5

It's not a book, but Lost in Space had an episode that's practically identical to what you're describing.

Plot excerpt from Wikia:

.... Later, Penny goes back the mirror in search of Debbie who has discovered a small bell somewhere. She eventually realizes that the bloop has been able to pass through the mirror somehow, and then return to the real world with the bell. Penny herself falls through the mirror and finds herself in a dark, mysterious world. There she meets a nameless boy about her own age who invites her to stay and have fun....