Complex sentence: Keller Dover (Hugh Jackman) and his family attend a Thanksgiving dinner at the house of their neighbors, the Birches, after which both families' young daughters, Anna Dover and Joy Birch, go missing.
Split into simpler sentences: Keller Dover (Hugh Jackman) attends a Thanksgiving dinner with his family at the house of their neighbors, the Birches. After dinner, the families' young daughters, Anna Dover and Joy Birch, go missing.