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I'm glad to add some context to my question. The paragraph where I found this expression is said by Kevin Costner who is talking on the script for a recent movie in which he plays the tittle rol: "Mrs Brooks", a sophisticated serial killer. He says: "I was taken aback by how good the writing was and what an interesting window it gave into a serial killer's life... it provided a really intriguing view into a despicable man's inner mind. It really rode the razor's edge."
I'm glad to add some context to my question. The paragraph where I found this expression is said by Kevin Costner who is talking on the script for a recent movie in which he plays the tittle rol: "Mrs Brooks", a sophisticated serial killer. He says: "I was taken aback by how good the writing was and what an interesting window it gave into a serial killer's life... it provided a really intriguing view into a despicable man's inner mind. It really rode the razor's edge."
There is an idiom "on a knife edge" = you have a very narrow path to follow. This takes it one step further as razors are generally much sharper and thinner than knives. The path is so narrow that you may well fall off - and in this context become insane.
Ride the razor's edge 
Re: Ride the razor's edge 
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