Here is an excellent plot summary, courtesy of Wouter:

The EWOKS, the courageous furry characters introduced in the blockbuster film RETURN OF THE JEDI brave awesome danger to aid two young space castaways searching for their missing parents.

One day Wicket's father, Deej was looking out for his sons, Weechee and Widdle, and instead found a crashed star cruiser with the human children Mace and Cindel Towani. Deej brought the children back to the village and nursed them back to full health. When Cindel was healing, she became friends with Wicket.

A question arose round the tribe not long after the children were back to full health. Where were their parents? Not long after that the question was answered. They were being held captive in the lair of the giant Gorax.

The children asked the Ewoks to help them free their parents. And so Deej and his three sons Wicket, Weechee and Widdle left with the children. The traveling caravan was soon joined by Chukha Trok, an Ewok lumberjack, and Kaink, an Ewok priestess. The eight adventurers found that there were many obstacles and new experiences like Barra monsters, deadly pools of water, and fairylike Wisties.

Mace made friends with one of the Wisties during the adventures. Wicket saved Mace's life from one of the deadly pools of water with a magic stick Logray given him during his apprenticeship. When they reached the lair of Gorax, Wicket and Widdle stay just inside the cave to protect Cindel. In the dark cliffs, Mace and the remaining four Ewoks had to climb a web to cross the cliffs, where they encountered a spider. While Kaink distracts the spider, Chukha Trok used his axe on the web so the spider fell down the cliffs. Then they faced Gorax

Down below Wicket faced the spider that just fell down the cliffs. Killing it with his own knife he saved Cindel and his brother. Up in the cave Mace's Wistie friend, Ezerina distracted Gorax while Chukha Trok and Mace freed the parents, Jeremitt and Catherine. During the battle, Chukha Trok was killed.

The Ewoks took the reunited Towani family back to the village and celebrated their good fortunes. The Ewoks were presented with white earwing headdresses. Wicket's father was proud to see his son wearing it.