TONIGHT'S MUST-SEE

"Heroes," 7 p.m., NBC. This terrific series has been tough to follow, as it darts on and off the NBC schedule. It returns Monday, with the season's final batch of new episodes. Before that, we can catch up by seeing these reruns. In the first, Peter is betrayed. Matt is overwhelmed when he meets the radioactive man and a new character, Hana. And Claire rages at her father figure, HRG. In the second, Matt and the radioactive man take HRG hostage and demand answers. The result leaves Claire embittered. In the third, Isaac paints his most terrifying painting. Also, we meet a new character, Candice.

OF NOTE

"CNN Presents: Larry King's 50 Years of Pop Culture," 2, 6, 10 p.m., CNN; repeats tomorrow. Here's a second chance to see the special that debuted Wednesday. It follows King, now 73, from his early days of Miami radio to his current show.

"Spring Watch USA," 5 p.m., Animal Planet. This ambitious series will watch spring arrive in different parts of the country. Vanessa Garnick, who had the surprisingly good series "Caught in the Moment," hosts with Jeff Corwin.

"Harry Potter and the Sorcerer's Stone" (2001), 7 p.m., ABC. The first of the Potter films starts wonderfully, as a mistreated lad is whisked away to wizard school. There are odd detours, but editing (to fit the time slot) will help.

"CSI: NY," 8 p.m., CBS. In this rerun, an arrow pierces both a playboy and his date, at a party. Who was the target? Or did Cupid just take things too literally?

"Saturday Night Live," 10:30 p.m., NBC. Scarlett Johansson hosts, with music from Bjork.