Dr. Lina Vos, an architectural cryptologist, is summoned to Ghent, Belgium to investigate a medieval chapel sealed for 400 years. The chapel's stained-glass windows impossibly predict a current supernova. Working with astrophysicist Henrik Maes and archivist Claire Devos (whose mother vanished in the chapel thirty years prior), Lina discovers the chapel is a nexus point where time barriers thin during celestial alignments. The windows encode mathematical equations describing quantum entanglement across time. They learn the chapel was designed by Elias Lichtmann, a possible time traveler who left messages specifically for them. As a crucial stellar alignment approaches, they discover three possible paths: maintain the cycle of hidden knowledge, sever the connection permanently, or expand it to all humanity with potentially chaotic consequences.