Thomas & Friends: Blue Mountain Mystery

Thomas & Friends is a children's media franchise based on the Railway Series books by Wilbert Awdry and created by Britt Allcroft in 1984 and owned by Mattel since 2012. The franchise revolves around the titular protagonist, Thomas the Tank Engine, as well as an ensemble cast of anthropomorphic steam locomotives and other vehicles, who all work on the Island of Sodor.

Synopsis from Wikipedia, CC BY-SA 4.0. Everything below written here.

Poster © the film's rights holders.