Life In 19x19

Oh, right, there was p2..
Thanks for the explanation!

Hmm.. difficult.
Black M4 seems to kill, and the only cases it won't will be if white can kill some black stones afterwards(probably the black corner, or s6), or do something around p8.
My initial guess was there must be something in the corner, but as I don't see a way to continue after white o1 or ...