This was supposed to be the first in a series of Professor Layton movies, with one releasing every winter.
The scenes that take place in present time take place inbetween The Curious Village and Diabolical Box/Pandora's Box while the scenes set in the past take place inbetween The Last Specter and Mask of Miracle
Talks of a Second Professor Layton movie was hinted at as far back as the First Movie's Production, however it never Materialized.