Narrative Connection
How these two moments in the story relate
Why These Connect
The narrative assertion
"The Doctor's discovery of the Cybermen's plan to weaponize the Gravitron (in Part 3) directly informs his deduction in Part 4 about how the Cybermen infiltrated the base, specifically tunneling through the storeroom."
inferred by llm_cross_episode_character
Why This Matters Across Episodes
The longer arc this connection carries
The Doctor's analytical reaction to the Cybermen's genocidal plan in Part 3 ('But that will kill everybody on the Earth. CYBERMAN 1: Yes.') drives his subsequent focus in Part 4 on the Gravitron's mechanism and the Cybermen's infiltration strategy. This establishes a direct causal link between the Doctor's knowledge of their larger plan and his tactical analysis of their intrusion method.
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.