Narrative Connection
How these two moments in the story relate
Why These Connect
The narrative assertion
"The Fourth Doctor's fatal fall from the Logopolis antenna directly causes his regeneration into the Fifth Doctor, whose subsequent crisis in the Dark Tower is the very reason the past incarnations must converge to rescue him."
inferred by llm_cross_episode_character
Why This Matters Across Episodes
The longer arc this connection carries
This is the most direct causal chain in the pairing. Without the Fourth Doctor's death in Logopolis, the Fifth Doctor is never born, and the central conflict of the Dark Tower featuring his rescue is never ignited.
About Causal Connections
A directly causes B. The first event sets forces in motion that produce the second. These are the load-bearing connections of plot--remove one and the story structure collapses.