Weekend TV watch

Swan lands her Hook — and it’s something to sing about, literally, as the long-awaited musical episode of “Once

Upon a Time” (Sunday at 8 p.m. on ABC) finally drops. In a flashback, a wish from the Charmings has everyone breaking out into song, including the Evil Queen, who is so not happy about it. While Emma and her pirate captain walk down the aisle in present-day Storybrooke, the Black Fairy and Gold look to crash the festivities.

How did a Tennessee teacher manage to kidnap one of his students and evade police for almost six weeks?

“20/20” (tonight at 10 on ABC) talks to the families of both perpetrator and victim and uncovers a complicated tale of abuse. The documentary “Batman

& Bill” helps right a wrong. It reveals how writer Bill Finger co-created the Caped Crusader, along with Bob Kane, who hogged the spotlight — and the financial rewards — for decades. DC now acknowledges the work of Finger, who created the Joker, Catwoman and more. The program streams on Hulu tomorrow, which also happens to be Free Comic Book Day across the nation.

MTV tries to be relevant by changing its annual MTV Movie Awards to the MTV

Movie & TV Awards (live Sunday at 8 p.m.). The thriller “Get Out” leads the nominations with six. Adam Devine of “Workaholics” hosts, and in a first, the channel has traded the best actor and actress categories for the gender nonspecific “Best Actor in a Film” and “Best Actor in a TV Series.” Best fight remains, but in a nod to today’s political climate, it has been tweaked to “Best Fight the System.”