A possible concise summary is:
Matt and Rebecca try to build a Lego house underwater for a date, but they get a mysterious pizza delivery with a note from Pumpkin Patch warning them that the GMI is on to them. They also get a text from Rocky with a video of RZ Twin at the gym, and they decide to go back to LA to help her.
Here are some possible facts extracted from the text:
1. Matt destroyed Rebecca's water slide to build a house underwater with giant Legos.
2. Matt wanted to have an underwater date with Rebecca as mermaids.
3. They received a pizza delivery with a note that said "They are on to you."
4. They suspected that the note was from Pumpkin Patch, who also texted Matt to warn him about the GMI.
5. They saw a video of RZ Twin at the gym where Rebecca had ninja training.