After the huge ruckus he created with Red-court, Harry Dresden almost went to turn himself into a cocoon to escape the grave agony of the tragedy of losing one of the dearest ones.
Death would have been rather normal than experiencing someone dear turning into the worst thing he despises the most.
Then again, when did our dear Harry has the luxury of dilly-dallying when he lives hand-to-mouth!
Though this time, Billy had to push him for it.

Summer Knight

With the pain and anger suppressing him, Harry Dresden let a harsh howling asking "Who are you?"
The sweet, sensual slytherin voice smiled saying "I am known by many names! However, you can call me by Mab, The Monarch of the Winter-court (fairy court)"
"A fairy Queen! Hells bells!" Harry almost shuddered in bewilderment and awe!

For the Fairy Realm there live two fairy Queens.
Both fairy Queens equally rule by rotation of power. Half of the time, the Winter Queen and another half of the time is ruled by Summer Queen. And that power distribution transpires naturally.
In this cycle, along with the fairy Queens, there remain two Knights as their lieutenants who are equally significant.

And on one day, Winter Queen, Mab appears in Harry Dresden's office with the proposal to help her with the investigation of a murder. And Mav came rather prepared that Harry could not refuse her in any way.

After the huge ruckus he had made with one of the essential members of The Red-court, the court demanded justice from the White council against Harry.
With being on the bad side of The White council, Harry only entangled himself in more grave misfortune after destroying an important member of the Red court.

To make it more intimidating, he heard the White council itself is coming to Chicago to settle the consequence. With so many sensitive issues on the plate, Winter Queens' proposal just made it worse for him.

Once again, cursing fate loud and hard Harry Dresden braced himself to face though puzzled and lost from where to begin with!
Let us see another show of Dresden once again!
Summer Knight
I assume after the last fight in Grave Peril, his power has started to manifest in a significant amount.
Harry's low stature about himself always conveys his power and physical built as insignificant! But guess things start to become interesting after the 3rd book.

Summer Knight was equally interesting as the story starts unfolding especially encounter with an important guest from the past!
As usual Dresden-Murphy's amusing combo and their usual humors, and a glimpse of Marcone as well! Not to mention, Bob plays his role and also cannot ignore even Mister!

For a quick series overview, you can have a look here-
Introducing "The Dresden Files"