It opened in 1881. 50 miles (80 km) long, it climbs through the Himalayan foothills to a summit of 7407 feet at Ghum, near Darjeeling. Grades are as steep as 1 in 18.
The line follows the Cart Road from Siliguri to Darjeeling, crossing and recrossing it frequently.
In 1999, it became the second railway in the world to be listed by UNESCO as a World Heritage site.
This production follows the "toy train" from near Siliguri, on the plains, to Darjeeling, and back.
It includes the famous loops and zig-zags; "crosses" at the stations (some of them unusual); a loco in trouble with a broken steam pipe, and lots of daily running, filmed in 1997 when the line was 100% steam operated.