The Portal is a mysterious object in that can transport things.
Connor and the others were going to use the portal, but due to Connor being damaged in an explosion the held off any contact with the object.
The engines were going to return to the portal, but Ivo Hugh was called on for a mission to stop The Diesel Army, and brought the others with him, getting Diesel and Charlie unitentionally killed in the process. After the destruction of the Road-Rail transporter, Connor and the others entered the portal, along with Harvey. The engines were transported to Tankopia via the portal so they could locate 089.
Lady used the Portal to rescue Sir Stephen Topham Hatt, Abraham Cody, General Phoenix Brown, Stan, and Kate, from an explosion. Instead of being taken to Tankopia like Connor and the others, they were transported to a small room with a turntable and various buffers. It was said to be "the space between space and time" by Lady.
- The portal is actually the roll of fishing wire used to pull the engines around.