One thing leads to another

Pro Tip 1/2

Chain Reactions

Understand that this phrase often implies a series of events, not just one outcome.

He missed the bus, one thing led to another, and he lost his job.

Pro Tip 2/2

Unintended Consequences

The phrase can express how unexpected results can arise from simple actions.

I told a small lie to avoid trouble, but one thing led to another, and it spiraled out of control.