Unfortunately, this book is out-of-print. I even emailed the author to ask her if she knew where I could lay my hands on a copy, but no luck. I thought I'd have to pay through my nose for a second hand copy on the net. But on my trip back to Singapore, I found this book and the sequel for SGD$2.90 each!
The Race for the Lost Keystone follows the sister-brother pair Kate and Phil as they discover that they're not as ordinary as they seem. Their family is actually the guardians of a bunch of magic stones called Heartstones. And if they have the Keystone (the most important of the bunch), they can even time travel. Sadly, their grandmother (the evil Lorabeth Lamptom) is evil and they team up with their Great-Aunt Elizabeth to fight evil.
What I remembered and loved most about the books were the gadgets. Great-Aunt Elizabeth's house is outfitted by a genius inventor called Harold. Can you imagine, cars which have an interior that can expand (no more squished me!), a "dried-and-dressed" (you choose an outfit and it bathes and dresses you), bedroom with a large apple tree and a waterfall - these were stuff that younger-me would love to have (present me would love it too!). The book is really enhanced by all these inventions that will appeal to any kid.
And, there's an exciting plot. It moves fairly quickly, and well, with the heartstones and the inventions, we get this mix of science and magic that made me thing "could this be real?".
Even though many many years have passed since I read this book, this is as good as I remembered it! I can't wait to read the sequel!