Causal
strong strength
Narrative Connection
How these two moments in the story relate
Why These Connect
The narrative assertion
"The Doctor directs Susan into the overflow pipe. Smithers plugs the drain, halting the water flow. They are safe but further water could flood the pipe. Later, Susan and the Doctor emerge from the plug hole, surprising Barbara and Ian after their ordeal in the pipes."
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.