The last time we saw Ra's al Ghul on Arrow, he was having a difference of opinion with his daughter Nyssa Raatko as to whether the murder of Sara Lance was a matter of interest for the League of Assassins.
When he returns on December 10, it seems he's decided that it is -- or at least that Nyssa is using his name to try and get results in the season's as-yet-unfruitful murder mystery.
You can check out the official synopsis for "The Climb," which airs following the first appearance of The Reverse Flash on The Flash the previous day, below.
“The Climb” — (8:00-9:00 p.m. ET) (TV-14, V) (HDTV)
RA’S AL GHUL GIVES OLIVER AN ULTIMATUM; DINAH LANCE PAYS LAUREL A VISIT — Nyssa (guest star Katrina Law) returns to Starling City and tells Oliver (Stephen Amell) that her father, Ra’s al Ghul (guest star Matt Nable) has given Oliver 48 hours to find Sara’s killer or the League of Assassins will start killing the citizens of Starling City. Laurel (Katie Cassidy) is stunned when her father (Paul Blackthorne) delivers a very special Christmas gift – her mother, Dinah (guest star Alex Kingston). Meanwhile, Ray (Brandon Routh) tries to make amends with Felicity (Emily Bett Rickards) and Oliver sets a meeting with Ra’s al Ghul. Thor Freudenthal directed the episode written by Jake Coburn & Keto Shimizu (#309). Original airdate 12/10/2014.