The city's first lady, Chirlane McCray, is set to unveil her plan to overhaul the city's mental health system later this fall. Her policy prescription will be significant, not only for New Yorkers in need of help, but also for McCray herself, who hopes this will become a signature issue she can put her very own stamp on. NY1's Grace Rauh filed the following report.

There was never a clear roadmap for Chirlane McCray when it came to being the city's first lady. The city's last mayor was divorced. And while Mayor Michael Bloomberg had a longtime girlfriend, Diana Taylor never tried to be an official first lady.

That's also been the case with Governor Andrew Cuomo's girlfriend, Food Network star Sandra Lee.

From the outset, though, it was clear things would be different with McCray. Her husband, Mayor Bill de Blasio, called her his most important advisor. And in the early months of his mayoralty, she was considered a co-mayor - her approval essential for anyone joining the team at City Hall.

The mayor appointed McCray to head the Mayor's Fund to Advance New York City. It's a non-profit group that raises private money for public causes. It gave her a position with official standing beyond her first lady title.

But it is McCray's more recent work on improving mental health services that is shaping up to be her legacy issue. In January, she announced she'd be spearheading an overhaul of the system.

"The truly shocking reality is that our city and nation is experiencing a mental health crisis," McCray remarked back in January.

It is a deeply personal subject for the first lady and Mayor. Their daughter, Chiara, has struggled with depression and drug use. And the mayor's father was an alcoholic who committed suicide. The first lady is expected to release her plan later this fall.

Announcing her mental health proposal will thrust the first lady back into the spotlight. It's a place where she has not always been comfortable. She's a former speech writer and often seems most at ease away from the cameras and behind the scenes.