Causal
strong strength
Narrative Connection
How these two moments in the story relate
From
Jamie and Polly confront tunnel uncertainty
S4E22
·
The Underwater Menace Part 4
To
Tunnel Collapse Under Rising Tide
S4E22
·
The Underwater Menace Part 4
Why These Connect
The narrative assertion
"Polly realizes they are beneath Zaroff's power source, describing vibration, which helps her realize that the glowing wall is crumbling because of those vibrations."
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.