During an investigation into the strange suicide of a scientist specialising in biochemical engineering, FBI special agents Mulder and Scully contend with memories of their missing son William.
Emma and Regina race to find Henry before Gold finds him; Snow, David and Zelena are imprisoned and face two disturbed individuals.
When a piece of Atom's suit falls into the wrong hands during a massive fight, professor Stein decides to turn to someone brilliant for help, his younger self. Carter helps Kendra recover an important memory.
Sara finds a way to hit multimillionaire Vandal Savage where it really hurts. Snart has an ulterior motive when he sends Jax to steal a valuable gem.
