A young adult (YA) fantasy. Must be doing well, I think the author got four sequels published. Kendra and Seth get sent to their grandparents place while their parents go on a cruise with a lot of family members. The children are not enthusiast about spending a month with grandparents they hardly know. The place turns out cooler than expected, a sanctuary for magical creatures, fairies, satyrs, a witch and others. Seth doesn’t listen well and gets turned into a walrus and later imprisoned in a huge glass jar for ignoring plain English instructions from his grandfather. After Seth opens a window on Midsummer’s eve (after he was told not to) a bunch of evil creatures fly in, wreck the house, and kidnap all the adults. With as lot of wandering around and guessing, Kendra comes up with a save for all the fallen.
We never hear of a mission that Kendra and Seth are supposed to go on. No scene where Gandalf explains the power of the Ring to Frodo. Far as I could see all Kendra and Seth wanted to do was wait for their folks to get back from that cruise and take them home again.
Not as good as the Rick Riordan YA fantasies.