In my opinion Shattered was the best episode of the season. It had the 
strongest characters of the show doing what they do best.  
Synopsis:
Lex gets the proof he needs that his father and Morgan Edge murdered Lex's 
grandfather. Rather than offing him, his father puts into motion a series of 
events that makes Lex look like he's crazy and ultimately does make Lex crazy 
(through a combination of false premises and drugs). Lex turns to Clark for help 
and Clark, the loyal friend does what he can to help Lex.
In the process, Lex begins to go nuts due to the drugging he's received and 
severely injures Lana who subsequently decides that she needs to stay away from 
Clark (oh boo-hoo) for her own safety. Just as Clark finds the link between the 
conspiracy, Edge, and Lionel, Lex does digging on his own and confronts Edge who 
tells him the truth.
Just as Edge is about to run over Lex with his car, Clark saves Lex but in 
the process is hit flat on by the car in front of Lex demonstrating Clark's 
invulnerability. Clark disappears just as the authorities reach Lex who seems to 
be raving.
The episode concludes with Lex in a mental hospital and the doctor assuring 
his father that Lex will forget his short term memory (luckily for Clark and 
Lionel). 
What made this episode great for me was the characters. Clark is a loyal guy 
and really pulled through for Lex despite the personal cost. It also seemed to 
mark an end of the Lana/Clark saga which many, if not most, fans have no care 
for anyway. 
Where they take it from here remains to be seeing.
9/10