on the double

idiomatic

(idiomatic) Rapidly or immediately.

Japanese Meaning

即座に / すぐに / 直ちに

When the storm warning came in, the crew moved on the double to secure the cargo.

嵐の警報が入ると、乗組員は貨物を固定するためにただちに動いた。

Sense（1）

(idiomatic) Rapidly or immediately.

Fortunately, help arrived on the double, and the victim's injuries were soon treated.