Narrative Connection
How these two moments in the story relate
Why These Connect
The narrative assertion
"The Doctor's insistence that Tegan board the Master's TARDIS in Logopolis binds her to his cause and continues the journey of the TARDIS crew. This commitment to the Doctor's dangerous life directly leads to the later situation where Nyssa is abducted by George Cranleigh, as the group remains together through subsequent adventures."
inferred by llm_cross_episode_arc
Why This Matters Across Episodes
The longer arc this connection carries
Tegan's arc is defined by her struggle between normal life and duty. The Doctor's firm urging in E28_1 forces her to choose the latter, setting a precedent for the companions' ongoing exposure to peril. The abduction of Nyssa in E18_4 is a direct consequence of the Doctor maintaining his team in active, hazardous missions.
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.