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 something

have an idea or information that is likely to lead to an important discovery. informal
See also: on, something