Rescue the third spy from the Rooftops above the Grease Monkey garage. You will need the Grapple Bowtie from the second spy.
(see related questions)
The (good guys) Spy Headquarters is right where you land on Spy Island : the tall shiny building. Enter and go upstairs to get your mission from Director D.
It is the Second Building on Main Street on Spy Island on poptropica.com.
To rescue the second spy, avoid the electrified windows. To rescue the third spy, you will need to go up one building to the rooftops, then to the far left and back again. This requires the Grappling Bowtie from the second spy. (see the related question)
Find a way to get to the top of the building
Go around them to the left. Go past the guarded building to the red building farther left. Climb to the TV tower, and then grapple back right to the antenna on the tall building's roof (a friendly spy suggests this).
in Uranus
JUMP!
The tallest building on Balding Avenue. It is where the third spy is held. (see related question)
On Balding Avenue, climb the building to the right of the Grease Monkey garage. Enter the "Rooftops". Put on your chameleon suit and grapple left, to the guarded building. Grapple left again, then up, and back right from the top of the red building (there is a friendly spy there).
The path to reach the third spy on Spy Island goes left from the Rooftops above the Grease Monkey garage. There is a guard who will attack you on the middle building, and no way to go straight up. So you go left to the reddish building and climb up. At the top, a helpful spy will suggest using the Grapple Bowtie to reach the tall antenna back to the right (atop the target building).
"Spy headquarters" is where the good-guys are, the large building where you land on Spy island. The hideout for B.A.D. is to the far right of the island, past Toupee Terrace. (see related question)
Before the release of Spy Island, the special "spy sunglasses" were on top of the Oracle building. They are no longer there, because you can copy them from the agents on Spy Island.