be on to (something)

be on to (something)

To discover, realize, or be in the process of doing something of great importance, value, or insight. Great work on this essay, Lindsay. I really think you're on to something here. Scientists now believe they may be on to a cure for cancer.
See also: on

be on to

1. Be aware of or have information about, as in They can't pull that trick again; we're on to them now. [Colloquial; second half of 1800s]
2. Discover something important or profitable, as in The researchers claim they are really on to something big. [Colloquial; mid-1900s]
See also: on

be on to

Informal
To be aware of or have information about: You'll never deceive us again; we're on to you.
See also: on