A skeptical historian discovers a portal to different time periods and must unravel its origins, only to realize it was created by a rival historian from the future who has been altering history, leading to a pursuit through time to preserve the true timeline.
A historian who is skeptical of the existence of time travel but is drawn into the mystery when they witness the portal in action.
The historian witnesses a historical figure step through the portal, leading to a pursuit through different time periods to unravel the mystery of the portal's origins and purpose.
In the end, the historian discovers that the portal was created by a future civilization as a way to study and preserve history. They choose to remain in the past, using their knowledge to make a positive impact on the world.
Twist: The historian realizes that the portal was actually created by a rival historian from the future, who has been altering events in the past to manipulate the course of history. The historian must now use their knowledge of the future to stop their rival and preserve the true timeline.