A girl goes out to the corner store and the family friend (who is later revealed to be the uncle) is acting terrified and very jumpy. He gives her her change and ushers her out the door as fast as he can. She finds a strange coin. She thinks it’s magic and when she gets home she loses it, but then finds it in her room after looking more carefully. She goes back to the man in the store and realizes some people are after him. She does something that causes a portal to open and she finds herself in another world, in a desert. There is a young man there, who is a guardian of the portal and something like a monk. The longer she is the there, the more of the language she understands (I think). She goes back home for a short period and decides she has to go back. She ends up in a prison where there are undead wraith men who are looking for the coin she has (it’s called something that sounds Irish). She and the monk kid escape and go to a cave to recover their strength. They journey back to a tribe. The undead come after them. She learns her father disappeared to this world years ago and is actually from this world. He went to England (Cambridge?) to learn more about their myths of worlds splitting away to understand what happened to their world. He is particularly interested in Tolkien. She goes home again and this time brings her brother with her to where her father taught. They speak to the professor who teaches his subjects now and he helps them with books that their father was studying. Another teacher is actually the undead in disguise. They flee him and all end up going back to the other world. The undead begin a war searching for the coin. Her brother is injured. She goes back to the prison to save the monk kid.