Monday's Highlights: 'How I Met Your Mother' on CBS
The Sing-Off: The groups perform a medley of Halloween-themed songs in this new episode (8 p.m. NBC).
Two and a Half Men: Jake (Angus T. Jones) is attracted to the girl who’s tutoring him in chemistry, but she’s got her eye on Walden (Ashton Kutcher) in this new episode (9 p.m. CBS).
Bored to Death: While spending time with Emily (Halley Feiffer), Jonathan (Jason Schwartzman) finds a surprise in a classified ad in this new episode (9 p.m. HBO).
Enlightened: As a distraction from the temptation to revert to her partying habits on her first weekend home, Amy (Laura Dern) persuades Levi (Luke Wilson) to go rafting in this new episode (9:30 p.m. HBO).
Hawaii Five-0: McGarrett (Alex O’Loughlin) and his colleagues are threatened by a homeless man — who could also be a suspect — while investigating the murders of a young couple who were filming a documentary about a Hawaiian burial site. Robert Englund guest stars in this new episode (10 p.m. CBS).
Rock Center With Brian Williams: “NBC Nightly News” anchor Williams hosts this new prime-time newsmagazine based in at New York City’s Rockefeller Center (10 p.m. NBC).
Castle: Castle and Martha (Nathan Fillion, Susan Sullivan) are taken hostage by a group of bank robbers wearing hospital scrubs and calling themselves by the names of doctors from classic TV shows in this new episode (10 p.m. ABC).
Ghost Hunters Halloween Live: As they’ve done for the past few Halloweens, Jason Hawes, Grant Wilson and their team investigate an allegedly haunted site in a six-hour live special. This year it’s the Pennhurst Asylum, a former institution for people with mental and physical disabilities located about an hour from Philadelphia (7 p.m. Syfy).
Night of the Living Dead: The granddaddy of all zombie flicks, this 1968 horror tale from George Romero has become a cult classic (6:30 p.m. TCM).
Football: The San Diego Chargers visit the Kansas City Chiefs (5:30 p.m. ESPN).
Photo: Monty Brinton / CBS