The Subtle Knife by Philip Pullman
Will Parry has to find his father. His father disappeared up North when he was a baby. Now some men are trying to find something his mother has hidden away. That article has information from or about his father. These men have broken in and searched his house. They will come back.
When they do, Will is in the house. He is able to escape from the house and starts running, the men chasing him. After his escape he finds a window in the middle of the road. When he steps through it, he discovers he is in a new, parallel world. Here is a place he can hide!
But there is more here in Chittagassee. There are spectres, witches, angels, gangs of children and Lyra Belacqua. Lyra has stumbled into this world after escaping from her own in The Golden Compass. She and Pantalaimon join forces with Will. Her alethiometer tells her he is the one who can help her. Or, more accurately, she is the one who can help him.
But Will and Lyra have to return to Will’s world for information. Lyra is trying to learn more about Dust, or Dark Matter. Will is trying to find clues to locate his missing father. There they meet the men who are chasing Will and a man who knows and is interested in Lyra. There is more danger both there and in the alternate world of Chittagassee. Will discovers there is a greater purpose for his life than he would have suspected.
This is a fascinating sequel. I have a dislike for novels where nothing is resolved. This one comes close to that, although Will’s search for his father is finished. Yet this one is a good bridge novel. Fortunately, my nephew has the third novel so I can finish this series fairly soon. The author pulls us into his vision. Chittagassee is an unusual world that needs more explanation. A way to find openings between different worlds is discovered. We receive hints as to Lyra’s deeper purpose in the overall scheme.