They're Alive! Part 2

''They're Alive! Part 2 is the 23rd episode of New Super Flynn-Fletcher Bros!''

Previously...
The gang found a document saying that Phineas' real dad is alive. Meanwhile, Doof causes Perry and Nega-Perry to swap dimensions! So Nega-Perry's here! Back with the gang, they tracked Mr. Flynn to a restaurant back in Jeffton, and fell down a trap door there!