After Thomas and Percy get spooked by a suspicious rumbling, the engines set off to figure out the secrets of the old mine inside Lookout Mountain.
| Actor | Role |
|---|---|
| AAaron BarashiThomas | Thomas |
| JJessica CarrollDarcy | Darcy |
| HHenri CharlesPercy | Percy |
| MMatt ColesWhiff | Whiff |
 Neil CroneGordon (US) | Gordon (US) |
 Glee DangoSandy (US) | Sandy (US) |
| HHolly DixonSandy (UK) | Sandy (UK) |
| BBruce DowSir Topham Hatt (US) | Sir Topham Hatt (US) |
| TTom DussekSir Topham Hatt (UK) | Sir Topham Hatt (UK) |