This is (obviously) the last in the series and covers the Zukertort version of the Colle Opening. White plays a Colle set-up with 1.d4 followed by 2.Nf3 and 3.e3 but then follows up with a fianchetto of his queen’s bishop with b2-b3.
This is a nice opening to play at club level because of the emphasis on plans and ideas rather than forced variations. It has also proven to be effective at GM level with players such as Artur Yusupov having adopted it extensively.
Here’s a nice miniature by Yusupov, from a rapid tournament in which he heavily outgraded his opponent. The mating finish was a neat one: