TV best bets: Sat., Nov. 5

November 5, 2016 GMT

8 p.m., HALLMARK CHANNEL: The Mistletoe Promise — After a chance meeting, Elise Donner and Nicholas Derr (Jaime King and Luke Macfarlane) discover that, while they may be strangers, they share a common disdain for the Christmas season. Dreading the prospect of several weeks of enforced faux cheer, the pair agree to offer mutual support as needed. As they inevitably spend more time together, however, Elise and Nicholas find their relationship is not merely one of convenience in this new 2016 romance.

8 p.m., HBO: How to Be Single — Fresh out of a long-term relationship, a recent college graduate (Dakota Johnson, “Fifty Shades of Grey”) moves to New York and befriends a partying co-worker (Rebel Wilson) at a legal firm who shows her how to have fun in this uneven 2016 romantic comedy adapted from a book of the same title by Liz Tuccillo. The comedy pros in the ensemble cast also include Alison Brie (“Community”), Leslie Mann (“This Is 40”), Damon Wayans Jr. (“Happy Endings”), Anders Holm (“Workaholics”) and Jake Lacy (“Girls”).

8 p.m., LIFETIME: Who Killed JonBenit? — Nearly 20 years after a murder that dominated headlines across America, this new docudrama revisits the events and investigation surrounding the death of petite junior beauty queen JonBenet Ramsey (Payton Lepinski), which remains unsolved today. Eion Bailey (“Once Upon a Time”) stars as Steve Thomas, lead detective on the case, while Michel Gill (“Mr. Robot”) and Julia Campbell (“Dexter”) play the victim’s parents, John and Patsy Ramsey, both of whom emerged as suspects during the proceedings.

9 p.m., BBC AMERICA: Dirk Gently’s Holistic Detective Agency — Dirk and Farah (Samuel Barnett, Jade Eshete) unearth their first major clue in the horrifying murder of Patrick Spring while digging into the victim’s past in the new episode “Rogue Wall.” Elsewhere, Todd (Elijah Wood) turns to the police, only to realize he may not be safe anywhere, and his sister, Amanda (Hannah Marks), struggles to cope with a looming presence in her life. Meanwhile, Bart and Ken (Fiona Dourif, Mpho Koaho) face a violent clash with a biker gang.

9 p.m., SYFY CHANNEL: 400 Days — To see whether four potential young astronauts — played by Brandon Routh (“DC’s Legends of Tomorrow”), Caity Lotz (“Arrow”), Ben Feldman (“Superstore”) and comic Dane Cook — have the right stuff for a space mission, they’re confined together for 400 days in a tight underground space intended to simulate a spaceship. Predictably, tensions rise and relationships fray as the weeks pass.