Causal
strong strength
Narrative Connection
How these two moments in the story relate
From
Arnold reveals tunnel demolition threat
S5E23
·
The Web of Fear Part 1
To
Doctor discovers explosives and Yeti threat
S5E23
·
The Web of Fear Part 1
Why These Connect
The narrative assertion
"Arnold revealing that the tunnels are about to explode leads Victoria to realizing the doctor is trapped in the tunnel with the explosives."
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.