Though aimed at a younger audience, the novel reminded me a bit of His Dark Materials trilogy. I think that honestly just may be the animal side kick here that reminded me of the daemon familiars in Pullman's story. Other than that, it's probably more reminiscent of Narnia, with a human girl chosen to cross the borders between two worlds and save a magical, wintery land - in this case one where favorite, beloved pets go after they die.
It took me a bit to get into this, and I wonder if maybe it was due to the way the language was translated. However, once Lin has used the twistrose key and is in Sylver, it picks up and flows along nicely. Lin and her parents recently moved to a new town due to a job opportunity for her mom, and Lin is lonely, having left her best friend behind. Shortly after they arrive, her pet vole (mouse like creature) Rufus dies, which makes the situation even worse. Missing the old games she would play with Rufus and her friend, she is playing one of them with herself, when she receives a mysterious key on her doorstep. When she goes down into the basement and uses it, she ends up in Sylver, and discovers that Rufus is already there, though he is 5 feet tall now. As he explains to her, he is one of the Petlings, and beloved pets of children end up in this realm after they die. There are four tribes of petlings, which encompass cats, dogs, rodents and birds, and then there are also a few wildlings in town and the area. These include a bear and a fox, and other animals that were pets under less usual conditions.
Lin is a Twistrose, and Sylver has a tradition of Twistrose children coming to the land in times of great need to save the realm. In this case, the last boy of a special family has gone missing, and he is the only one that can do the spell required to keep the magic in Sylver, and prevent its ultimate demise. However, Lin soon learns that things are much more complicated as there are different factions in the town who seem to have different ideas of how this can best be accomplished. Additionally, there seems to be a whole other, bigger plot going on that could hinder Lin and prevent her and Rufus from accomplishing her mission. Lin is very adventurous, but since she and Rufus don't know who to trust, they also quickly find themselves in trouble and getting into various tight spots.
I thought the story was very sweet and enjoyable, but I also feel like it is definitely open for a sequel. The villain's backstory is only touched upon towards the end of the novel, and I would have loved to hear more about his development and life since what is revealed is sad and tragic. This was definitely aimed at a slightly younger audience than I usually read but it still managed to have some rather tragic and poignant moments throughout.