Looking for good bedtime adventure story plots for kids, know where I can find some?

I have kids ages 7 and 4 and I struggle to come up with clever bedtime stories to tell them from my head. Is anyone familiar with a site that just contains plot abstracts that I can embellish on my own? They like adventure and mystery stories—you know, stories about kids that travel to a magical island and encounter pirates and animals and whales with magical powers. Is there like a Hardy Boys equivalent for young kids? Any suggestions?