Matthias sought him out to learn the whereabouts of the snake Asmodeus Poisonteeth. Infuriated with the bird's disbelief in his quest succeeding, Matthias struck a deal with him. If Matthias killed Asmodeus and brought back Martin's sword, Captain Snow was never to eat a mouse or shrew again, and would also apologize to Gingevere for his behavior.
After Matthias returned from the quarry, Captain Snow, shocked that he was able to do so, reluctantly kept his end of the deal, much to the delight of Matthias and the Guosim. He then apologized to Squire Julian Gingivere, but to his surprise Julian apologized to him, they both agreed to share half the blame, then Captain Snow went back with Julian Gingevere to the farm. After the final battle of the Late Rose Summer Wars, Captain Snow and Squire Julian Gingivere killed all the vermin trying to escape into Mossflower Woods. Captain Snow is perhaps the only known owl in the Redwall series to have a villainous status.