The missing painting
The missing painting is the missing piece of a narrative made up of Isaac's paintings when put together like a comic book.
While Isaac and Peter work together to figure out the meaning of "Save the cheerleader, save the world," they discover that Isaac's paintings can be arranged to tell a story like a comic book. Once this is done, there is a missing piece in the upper-left corner of the full picture. Isaac says that he painted a piece the correct size, but that Simone has taken that painting to her gallery. Isaac claims he cannot describe what was in that painting because he was high when he painted it.
Peter leaves a message on Simone's answering machine saying that he needs to see the painting because it will help save the world. She later tells him that it was sold to a guy named Linderman in Las Vegas.
Peter askes Nathan to help him get the painting back. Nathan contacts Mr. Linderman by phone but the part of the conversation we hear is inclusive as to if the painting will be returned. Nathan tells Peter that Linderman will not return the painting.