奇襲をうけた僕はなすすべもなく敗北してしまい....その後肉体を陵辱されてしまった
Japandict.com, gives these meanings:
なすすべもなく = having no choice, at a loss for what to do, at one's wits' end, helpless
But would like more context to understand it, for example I see the words:
なす=為す, the particle も, the negative form of なく=ない
I don't know if I'm right