You arrived at the abandon Danville. You walked near Phineas and Ferb's backyard and heard Isabella singing to Phineas no longer trusting him. She doesn't hear you walk by though

Secrets uncovered, was this a deceit? A prevarication, of what seemed to be! Now left to sustain, my pains persevere... A summer of freedom that failed to remain sincere...

Do you know what you're going to do? Because it's true... There's nobody left BUT YOU!