According to the Revenge of the Sith novelization by Matthew Stover (2005), Count Dooku was deceived by Darth Sidious into thinking that the plan was to kill Obi-Wan, turn Anakin to the Dark Side, and allow himself to be captured by the Republic. After some time of captivity, Dooku would defect to the Republic and join with Sidious/Anakin to create the new Empire. This is not completely insane since according to the novel Dooku is respected by the citizens of the galaxy as a sort of Robert E. Lee figure.
Below are excerpts from the novel. Dooku looks forward to captivity and serving in the new Empire:
"It will be," he said slowly, meditatively, as though he spoke only to
himself, "an embarrassment to be captured by him." The voice that
answered him was so familiar that sometimes his very thoughts spoke in
it, instead of in his own. "An embarrassment you can survive, Lord
Tyranus. After all, he is the greatest Jedi alive, is he not? And have
we not ensured that all the galaxy shares this opinion?" "Quite so, my
Master. Quite so." Again, Dooku sighed. Today he felt every hour of
his eighty-three years. "It is ... fatiguing, to play the villain for
so long, Master. I find myself looking forward to an honorable
captivity."
A captivity that would allow him to sit out the rest of
the war in comfort; a captivity that would allow him to forswear his
former allegiances-when he would conveniently appear to finally
discover the true extent of the Separatists' crimes against
civilization-and bind himself to the new government with his
reputation for integrity and idealism fully intact. The new government
... This had been their star of destiny for lo, these many years. A
government clean, pure, direct: none of the messy scramble for the
favor of ignorant rabble and subhuman creatures that made up the
Republic he so despised. The government he would serve would be
Authority personified. Human authority. It was no accident that the
primary powers of the Confederacy of Independent Systems were
Neimoidian, Skakoan, Quarren and Aqualish, Muun and Gossam, Sy
Myrthian and Koorivar and Geonosian. At war's end the aliens would be
crushed, stripped of all they possessed, and their systems and their
wealth would be given into the hands of the only beings who could be
trusted with them. Human beings. Dooku would serve an Empire of Man.
And he would serve it as only he could. As he was born to. He would
smash the Jedi Order to create it anew: not shackled by the corrupt,
narcissistic, shabby little beings who called themselves politicians,
but free to bring true authority and true peace to a galaxy that so
badly needed both. An Order that would not negotiate. Would not
mediate. An Order that would enforce. The survivors of the Jedi Order
would become the Sith Army. The Fist of the Empire.
Sidious explains the plan to kill Obi-Wan to Dooku:
"Kenobi must die. Today. At your hand. His death may be the code key
of the final lock that will seal Skywalker to us forever."
Dooku
understood: not only would the death of his mentor tip Skywalker's
already unstable emotional balance down the darkest of slopes, but it
would also remove the greatest obstacle to Skywalker's successful
conversion. As long as Kenobi was alive, Skywalker would never be
securely in the camp of the Sith; Kenobi's unshakable faith in the
values of the Jedi would keep the Jedi blindfold on Skywalker's eyes
and the Jedi shackles on the young man's true power.
Still, though,
Dooku had some reservations. This had all come about too quickly; had
Sidious thought through all the implications of this operation? "But I
must ask, my Master: is Skywalker truly the man we want?"
"He is
powerful. Potentially more powerful than even myself."
"Which is
precisely," Dooku said meditatively, "why it might be best if I were
to kill him, instead."
Dooku sees the plan as a path to Sith Masterhood:
Improving upon his Master's plan was near to impossible; his own idea,
of substituting Kenobi for Skywalker, he had to admit was only the
product of a certain misplaced sentimentality. Skywalker was almost
certainly the man for the job. He should be; Darth Sidious had spent a
considerable number of years making him so. Today's test would remove
the almost. He had no doubt that Skywalker would fall. Dooku
understood that this was more than a test for Skywalker; though
Sidious had never said so directly, Dooku was certain that he himself
was being tested as well. Success today would show his Master that he
was worthy of the mantle of Mastery himself: by the end of the coming
battle, he would have initiated Skywalker into the manifold glories of
the dark side, just as Sidious had initiated him.
More of the plan involving Anakin and the destruction of the Jedi Order:
With his heroic capture of Count Dooku, Anakin Skywalker will become
the ultimate hero: the greatest hero in the history of he Republic,
perhaps of the Jedi Order itself. The loss of his beloved partner will
add just exactly the correct spice of tragedy to give melancholy
weight to his every word, when he gives his HoloNet interviews
denouncing the Senate's corruption as impeding the war effort, when he
delicately-oh, so delicately, not to mention reluctantly-insinuates
that corruption in the Jedi Order prolonged the war as well. When he
announces the creation of a new order of Force-using warriors. He will
be the perfect commanding general for the Sith Army.
Dooku could only
shake his head in awe. And to think that only days earlier, the Jedi
had seemed so close to uncovering, even destroying, all he and his
Master had worked for. But he should never have feared. His Master
never lost. He would never lose. He was the definition of unbeatable.
How can one defeat an enemy one thinks is a friend? And now, with a
single brilliant stroke, his Master would turn the Jedi Order back
upon itself like an Ethrani ourobouros devouring its own tail. This
was the day. The hour. The death of Obi-Wan Kenobi would be the death
of the Republic. Today would see the birth of the Empire.
"Tyranus? Are you well?"
"Am I . . ." Dooku realized that his eyes had misted.
"Yes, my Master. I am beyond well. Today, the climax-the grand finale
the culmination of all your decades of work ... I find myself somewhat
overcome."
"Compose yourself, Tyranus. Kenobi and Skywalker are nearly
at the door. Play your part, my apprentice, and the galaxy is ours."