Is it ethical to write someone's thesis for them?

This is for a grad student completing her Masters in Psychology. She’s written the first chapter containing the literary research, and now wants to hire me to write the rest – which includes (apparently) doing some research and conducting interviews for her, along with writing the thesis (and the conclusions of the interviews) myself.

I’m looking for answers from people who’ve been through this process of writing a Master’s thesis. Is this ethical? Or is it cheating?