Returned: March 17 (airs Mondays at 9 pm/ET, CBS) Number of new episodes: 7

Where we left off: Charlie (Charlie Sheen) started growing disenchanted with the single life and Alan (Jon Cryer) continued his quest for Ms. Right. "For both these guys, it's a pivotal time, because they are hit­ting the big 4-0 and they have to grow up," creator Chuck Lorre says. "Charlie doesn't want to be the old guy in the bar." What's next: Puberty hits Jake (Angus T. Jones), and Charlie will teach him how to pick up women. "They take out a mother and daughter," reveals Lorre, "and it does not go well." Also, the story line of the brothers' wacky mom (Holland Taylor) marry­ing wealthy Teddy (Robert Wagner) continues. Criminally funny?: The scribes of CSI and Two and a Half Men will swap jobs and write an episode of each others' shows to air in May. CSI executive producer Carol Mendelsohn says, "We're going to help them with the forensics aspects, and they are going to help us with comedy."