In the Doctor Who episode (Series 6, Episode 8), the Doctor, Amy, and Rory travel to 1938 Berlin. This episode serves as a pivotal origin story for River Song , revealing her childhood as "Mels" and her ultimate transformation. Key Plot Developments
: The Doctor gives River her iconic blue TARDIS-shaped diary , marking the beginning of their complicated, "backwards" timeline together. [S6E8] Let's Kill Hitler
: After seeing the Doctor’s kindness and learning about her parents' love for her, River uses all her remaining regeneration energy to bring him back to life, becoming fully human in the process. Character Revelations In the Doctor Who episode (Series 6, Episode
: It is revealed that the TARDIS itself taught River how to pilot it, which explains why she is often more proficient than the Doctor. : After seeing the Doctor’s kindness and learning
: While biologically human (conceived in the Time Vortex), medical scans in this episode suggest River may have two hearts , mirroring Time Lord physiology. Episode Significance River Song | Tardis - Doctor Who Wiki
: Amy and Rory's childhood friend Mels is revealed to be their daughter, Melody Pond . After being shot by Hitler (who is promptly shoved into a cupboard), Mels regenerates for the first time on-screen, becoming the woman known as River Song .