TiVo Guide Week of May 11, 2009 *spoiler alert*

“The Big Bang Theory” In the second-season finale, Leonard gets ready for a three-month long science trip, and he and Penny come to terms with their feelings for each other. Monday at 8 on CBS.

“Gossip Girl” Lily flashes back to her teen years in the '80s, recalling the time she was thrown out of boarding school and reconnected with her family in L.A. Elsewhere, Nate and Blair's prom is less than perfect, and Serena and Lily argue about Serena's arrest. No Doubt portray an '80s band. Teenage Lily: Brittany Snow. Rick Rhodes: Andrew McCarthy. Cece Rhodes: Cynthia Watros. Carol Rhodes: Krysten Ritter. Monday at 8 on The CW.

“Castle” In the Season 1 finale, a plastic surgeon is found murdered in his car, and the ensuing probe involves surgery-obsessed patients and hush-hush procedures. Elsewhere, Alexis attends her first prom; and Castle discovers extremely unsettling information about Beckett's past. Monday at 10:02 on ABC.

“American Idol” The Top 3 finalists sing two songs each in a performance edition. The show's 300th episode. Tuesday at 8 on Fox.

“Biggest Loser: Couples” The winner of the $250,000 grand prize is revealed in the seventh-season finale. Also: the third finalist is chosen; the at-home players weigh in for the $100,000 prize; and two potential contestants for next season are presented for viewer voting. Tuesday at 8 on NBC.

“Real Housewives of New Jersey” The worlds of five indulged ladies from the Garden State are tracked in this real-world series, an entry in the soapy "Real Housewives" franchise. The cast includes two sisters who are married to two brothers. Tuesday at 11 on Bravo.

“America’s Next Top Model” The winner is selected by the judges as the 12th season concludes. The three remaining ladies are reduced to two after the trio shoot a cosmetics commercial. The two remaining contestants walk and crawl down the final runway to determine the top model. Wednesday at 8 on The CW.

“Lost” In the Season 5 finale, Jack runs into stiff opposition to his plan to set things right on the island, while Ben gets a tough job assignment from Locke. Flashbacks focus on Kate, Juliet and Sawyer. Wednesday at 9 on ABC.

“Criminal Minds” A killer releases a deadly virus into the open air, and one of the agents risks his life to stop the threat. Lee Whitworth: Dan Lauria. Wednesday at 9 on CBS.

“Smallville” In the eighth-season finale, Oliver takes the lead when Clark exhibits resistance to killing Doomsday, and Chloe finds herself caught in the middle of the situation. Meanwhile, a fight between Lois and Tess takes a surprising turn. Thursday at 8 on The CW.

“Bones” In the fourth-season finale, a murder at a nightclub where Mötley Crüe, who appear as themselves, are performing makes suspects out of the entire Jeffersonian team, who go to extremes to solve the case and clear their names. Guest stars include Eric Millegan, Ryan O'Neal and Brendan Fehr. Thursday at 8 on Fox.

“30 Rock” Season 3 closes with Jack trying to connect with his biological father (Alan Alda), but the elder's health begins to suffer. Elsewhere, Liz gains fame as a relationship expert. Among the music artists appearing: Sheryl Crow; Mary J. Blige; Elvis Costello; Clay Aiken; and Adam Levine of Maroon 5. Thursday at 9:31 on NBC.

“Ghost Whisperer” In the fourth-season finale, Melinda fears for her unborn child after a surprising visitation by a ghost. Carl the Watcher: David Clennon. Josh Bedford: Bruce Davison. Friday at 8 on CBS.

“Prison Break” In the series finale, old friends (Amaury Nolasco, Rockmond Dunbar) turn up as Michael makes one last effort to get Scylla into responsible hands and take down the Company. Sofia: Danay Garcia. Lang: Barbara Eve Harris. Friday at 8 on Fox.

“NUMB3RS” The fifth season concludes with Amita being kidnapped by a manipulative guru (James Callis) who favors female followers. Don's team frantically searches for her while a distraught Charlie attempts to uncover the motive behind the abduction. Friday at 10 on CBS.

“Beverly Hills Groomer” A spin-off from 'Groomer Has It' following the series' first winner, Artist Knox, as he works toward opening his own salon in Beverly Hills. In the first episode, Artist cruises Rodeo Drive in his mobile grooming truck in search of clients. Later, his brother Desmond helps him scout out a hip dog park. Saturday at 10 on Animal Planet.

“MADtv” Fred Willard hosts "MADtv Gives Back" in the series finale, which features alumni Alex Borstein, Mo Collins, Will Sasso and Debra Wilson Skelton reprising their popular characters. Saturday at 11 on Fox.

“Saturday Night Live” Season 34 closes with Will Ferrell serving as host. Green Day are the music guest. Saturday at 11:29 on NBC.

“Survivor: Tocantins---The Brazilian Highlands” The jury questions the final castaways before voting for a winner. Jeff Probst is the host. Sunday at 8 on CBS.

“Desperate Housewives” Season 5 finale: Gaby runs into a down-on-her-luck old acquaintance; Tom decides to go back to school (much to Lynette's dismay); Orson threatens Bree with blackmail; and Dave makes a "friendly" gesture to Susan. Roberta: Lily Tomlin. Karl: Richard Burgi. Sunday at 9 on ABC.

“Saturday Night Live Just Shorts” Host Andy Samberg serves up a pool of short films, faux commercials, animated pieces and digital shorts from the archives of "Saturday Night Live." Sunday at 9 on NBC.