Here is a possible concise summary of the text:
Jimmy has a nightmare about giant robot claws that snatch Sarah away. He wakes up and finds a postcard from Rolf's relatives, who are visiting from the old country. He thinks his dream has come true and joins Jonny in warning the others about alien invaders. The kids go to Rolf's house and find it surrounded by strange machines and creatures. They attack them with homemade weapons, but discover that they are actually Rolf's family members, who have different customs and traditions. Rolf invites them to join the celebration, but they are scared and annoyed by his relatives' behavior.
Here are the key facts extracted from the text:
- Jimmy had a nightmare about giant mechanical claws that snatched Sarah away.
- Jonny claimed that there were flesh-eating aliens invading Rolf's house.
- Ed was experimented on by Rolf's relatives, who were visiting from the old country.
- Rolf's relatives had heat vision and used the kids' clothes as emergency bibs.
- Kevin led an attack on Rolf's house with homemade weapons.
- Edd developed a sub-zero battle suit to protect them from the heat vision.
- Eddy wanted to capture an alien and become rich.
- Rolf invited the kids to join his family's festivities.