Cross-cut after tower peep
This material is related to the double crosscut to connect page and deals with the same crosscut tesuji - it should perhaps be organized differently
There is only sense in the tower peep if followed through with a cut. is the severest of the two cuts.
Now Black has a tesuji up his sleeve. First he exchanges - (if unanswered, ladders or nets become possible). Next comes the keima attachment of which White naturally answers with the outside hane.
The cross-cut of captures the marked cutting stones. There is nothing White can do about it. The atari of a, c will be answered with b, d respectively.