Causal
strong strength
Narrative Connection
How these two moments in the story relate
From
Romana discovers the micromeson scanner
S17E5
·
City of Death Part 1
To
Discovery of Mona Lisa plot during tail
S17E5
·
City of Death Part 1
Why These Connect
The narrative assertion
"Romana discovering they are being followed leads to her finding the micromeson scanner, which the Doctor uses to deduce the alien plot to steal the Mona Lisa."
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.