This is the story of 500 rats on the West Side Highway and one who ventured east.

They were not your typical city rats. They were albinos, white with pink eyes, the kind people keep as pets or tinker with in labs or raise to feed to snakes.

Last July, they began to appear in a kite-shaped median between the highway and an exit lane onto West 57th Street, across from a Sanitation Department garage: first a few rats, then a few dozen, then so many that they were a blur of white in the undergrowth, a scurrying time-lapse.

How the rats got there remains a mystery.

But one of them was Rose. She was near the end of childhood, 5 weeks old and fully furred.

There was no food or water for the rats on their little island. Many of them ran out onto the 10-lane highway, made for the riverfront, met with bad ends. (It did not help that albino rats are mostly blind.)