Storm tries to negotiate peace with Callisto, who has turned increasingly militant and has taken in Marrow, who recently attacked two police officers. However, she turns Marrow back over to Storm, saying that Callisto can no longer guarantee the safety of mutants who she associates with–given her recent turn towards violent means to protect mutants.
Note that the similarly numbered Uncanny X-Men #179 also had a big showdown with Storm and Callisto.