"It's an extremely positive book, but it's got some surprises in there," Collins said, giggling.
Who's likely to be at the receiving end of the shock?
She won't say.
"Then maybe next summer I'll start the next one."
Collins spent her Christmas break putting the finishing touches on the book, which was first announced in August last year.
She earlier indicated it would cover events in 2014.
That was the year journalist Nicky Hager's Dirty Politics was published, detailing links between Collins and controversial former blogger Cameron Slater.
Collins was forced to resign as Justice Minister shortly before the 2014 general election, but was later cleared of wrongdoing.
She has said the book will describe what happened behind the scenes during the period.