Yeah, SUDDEN IMPACT doesn't sound exactly thrilling, but its plot does fit in line with the franchise.

If Harry went vigilante at the finale of DIRTY HARRY, then he had to fight cops who went vigilante in MAGNUM FORCE, then SUDDEN IMPACT is Harry having to contend with someone trying to be vigilante in her need for her own revenge. Vigilantism is a door that swings both ways, though with Harry, he simply blows it away with his Magnum.

While we're talking pre-HARRY Eastwood, while his spagetti westerns were great, I enjoyed his solid directorial debut PLAY MISTY FOR ME*, but my personal favorite of pre-HARRY Eastwood was probably WHERE EAGLES DARE, which was his biggest hit until DIRTY HARRY.

*=Or, the smart version of FATAL ATTRACTION.