Causal
medium strength
Narrative Connection
How these two moments in the story relate
From
Susan’s farewell complicates the escape
S1E18
·
Rider From Shang-Tu
To
Tegana witnesses betrayals and surveillance
S1E18
·
Rider From Shang-Tu
Why These Connect
The narrative assertion
"Ping-Cho giving Susan the key is a catalyst for the Doctor and the others to try and escape during the night."
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.