Nigel Bumble is the eager, accident-prone young Rook at the heart of the Train Hideout stories. He follows Agnes around London until she lets him join, gets arrested after a night out, and thanks the twins by stealing a Gatling gun for the train.
Nigel tails Agnes on her errands so clumsily that she asks Evie for help. Trying to blend in with two workers, he blurts out that Agnes is a Rook without realising they are Blighters, and Evie has to deal with the reinforcements. Back at the train, Agnes and Evie pull him inside for questioning and he is taken on as a cleaner.
After a night drinking with other Rooks he is caught up in a Blighter's murder and arrested. Evie destroys the evidence against him, leaving the arresting sergeant with nothing to show the Chief Inspector, and Nigel goes free.
To say thank you, Nigel gets a Blighter gang drunk and walks off with their Gatling gun, then has it mounted on the train. When the Blighters attack, Jacob uses it to fight them off until it overheats and has to be abandoned.