Causal
strong strength
Narrative Connection
How these two moments in the story relate
From
Chumbley reveals self-destruct plan
S3E4
·
The Exploding Planet
To
Chumbley sacrifice secures TARDIS escape
S3E4
·
The Exploding Planet
Why These Connect
The narrative assertion
"The Chumbley's sacrifice is directly tied to protecting the Doctor, Steven, and Vicki as they retreat to the TARDIS, enabling their eventual escape."
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.