From the announcement:
Welcome, agents. We don’t have much time. After all, you could be embarking on your next mission as early as today—the mission we’ve designated Lumen Fidei.
No one here at the T.I.M.E Agency can predict exactly what you’re going to find, but we’ve done our best to acquaint you with what we currently know in our advance briefings.
Of course, you know the destination of your mission—medieval Spain near the end of the decades-long Reconquista—and your objective. An anomalous stone, rumored to have unexplainable powers, has been discovered in this era. Your mission is to travel into the past and retrieve this stone, bringing it back for safe keeping within the walls of the T.I.M.E Agency.