Castle is convinced they've stumbled onto a Da Vinci Code style conspiracy when strange symbols are found in a murdered woman’s apartment.
Lex sets out to confront professor Fine (James Marsters); Clark meets a beautiful seductress, who learns of his powers.
Kiera and Carlos investigate a video game company that is the only tie between two murder-suicides.
While investigating a Marine's murder, the NCIS team uncovers a labyrinth of live-streaming spy cameras hidden in the rooms of a Virginia motel.
Clark discovers that Lana is missing; Tess reveals what really happened to Lana when she woke up from her Brainiac-induced coma; Tess is shocked by what she discovers in a secret LuthorCorp facility.