If black plays first, he can live with . If at then at a. Black wins the capturing race and takes the white stones.
If white plays first, he can kill the black group. See the variation below, where black plays at either of the a points. The common theme for this and the other variations is that white can make an eye in the stomach.
abc If Black lives by playing 1 then it is the obvious play to make for white as well, and it appears to kill. A and b are mia for gaining an internal eye, after which White can kill by fill the one external liberty.