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3. be on the case

be on the case

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be on the case

1. To be working diligently on a particular task. Yes, there is a problem with my car, and my mechanic is on the case.

2. To be investigating something. When my youngest thinks her older brother is doing something suspicious, she is on the case—she's the best spy I could have asked for! The system crashed overnight, but IT is on the case, so it should be back up soon.

See also: case, on

be on the case

to be doing what needs to be done in a particular situation 'We need to book a flight before it's too late.' 'Don't worry, I'm on the case, just leave it to me.'

See also: case, on