Mulberry discovered that Cedric possessed evidence exposing a criminal conspiracy involving powerful nobles.
Mulberry believed Cedric intended to sell the information, causing widespread chaos and possibly sparking a war.
When Cedric refused to surrender the documents, Mulberry murdered him.
Method
During a blackout caused by a storm:
- Mulberry disguised themself as Heron.
- Entered Cedric's compartment.
- Stabbed Cedric with Ruby's stolen letter opener.
- Planted misleading evidence throughout the train.
- Returned to their cabin.
The goal was to ensure every suspect appeared equally guilty.