“This Is 40,” 7 p.m. to 9:15 p.m., HBO (2012)
What happened after “Knocked Up”? We find out in Judd Apatow's semisequel, which finds Pete (Paul Rudd) and Debbie (Leslie Mann) dealing with marriage, parenthood and turning the big 4-0.
“The Cheating Pact,” 7 p.m. to 9 p.m., Lifetime (new)
After three high school students convince another girl to take college entrance tests for them, the test taker is found dead, and one student is framed in the murder.
“Debbie Macomber's Cedar Cove,” 7 p.m., Hallmark (new)
After Stan separates from his wife, he returns to Cedar Cove hoping to reunite with Olivia.
“Cupcake Wars,” 7 p.m., Food Network (new)
Film critic Leonard Maltin is a judge as cupcakes are made to celebrate the rerelease of “The Wizard of Oz.”
“Hell on Wheels,” 8 p.m., AMC (new)
With Gen. Grant's decision looming and Cullen and Elam paying Durant a visit, a gang of riders attacks Cheyenne.
“48 Hours,” 9 p.m., CBS (new)
The 26th season of this news magazine gets underway with an investigation into the murders of two teens 32 years ago.
“Saturday Night Live,” 10:29 p.m. to midnight, NBC (live)
Tina Fey is back at Rockefeller Center to host as the comedy show starts its 39th season. Arcade Fire is the musical guest.