Three stars may be a bit mean. I struggled with this one and as such was disappointed with it. The writing was solid and in general the characters were good but I felt the UNIT team including jo were massively underused. They just didn't seem to be needed in the story and felt sidelined. Again this was a book I read when I was unwell, so I fully intend to read it again but I do keep putting it off. I just didn't feel it worked that well. It's a huge shame as a third doctor/roger Delgado master story is a wonderful thing. That element of the book worked the best and I wonder if it would have been better to set it later when the doctor was travelling again therefore negating the need for UNIT. One thing I found particularly odd is the cover. The biggest selling point of this book is the doctor/master element and I don't understand why Jon pertwee or roger Delgado aren't featured on the cover. Needless to say if when i read it again i enjoy it more I'll consider a new updated review.