Daniel is watching a film of experiments done on the Stargate in 1945 and sees that they actually manage to turn it on. A man wearing a diving suit goes through the gate. Daniel shares this information with Catherine Langford. She tells Daniel that the man who walked through in 1945 was Dr. Ernest Littlefield who she was supposed to marry. Her father told her that he died in an explosion. Daniel then shows her the adress the the planet that Ernest went to.
Daniel returns to the SGC with Catherine. Captain Carter finds out that the planet was not on the Cartouche found on Abydos (Meaning the Goa'uld haven't been there, which also supports that the Goa'uld didn't build the stargate system after all.) Catherine comes with them to the planet. On the other side, they find an old castle on a cliff. SG-1 finds Dr. Littlefield in the castle. They find out that the reason Ernest hasn't tried to come back is because the DHD's central Part (The dome) was broken by a piece of rock that fell from the castle years ago. It doesn't work at all.
While Carter and Teal'c try to fix it, Earnest shows them a room with 4 distinct alien languages (Which are the Asgard, The Furling, The Ancients and the Nox which we will later discover in the episode entitled "The Fifth Race".) There is a device that projects a holographic representation of the elements (146 of them). Daniel reads Dr. Littlefield's notes which helps him understand about the languages and the elements. Meanwhile, Captain Carter tries to link the DHD's power source directly to the Stargate. It works, or so they think. It causes the castle to shake, then the DHD falls through the floor, and they have to find a new way to get home. SG-1 wants to break open the device that shows the elements. Teal'c shoots it with his Staff weapon but the device is left intact. Jack thinks that they should try "The old Ben Franklin thing" to provide energy for the gate to work. SG-1 hooks up wires and metal parts from the M.A.L.P. to the roof to attract lightning from the storm. Dr. Littlefield has Teal'c put his helmet at the top the roof. A bolt of lightning hits it, which transfers to the Stargate, and Teal'c starts to dial Earth manually while Jack gets Daniel - Daniel wants to stay.
The gate is open. Dr. Littlefield gets Daniel to come with them. Catherine and Earnest Return through the gate. O'Neill and Daniel are still on the planet. The wormhole is destabilizing, Jack and Daniel have only a few seconds left. They arrive on Earth at the last second.
They try to dial back to the planet but the castle fell into the ocean which buried the gate