Apparently "What We Leave Behind" (the mid-season cliffhanger from December) was all the lessons learned from the first half of the mildly entertaining 1st half of Arrow season 5. That's my takeaway from the 2nd half premiere "Who Are You?" Here now, the recap.

Oliver and Felicity are speechless at the sight of Laurel 'Black Canary' Lance in the Arrow Basement, resurrected by a white light and a Waverider full of future tech at the hands of her White Canary sister Sara. They fill her in on the alcoholic state of affairs with her father and let her use the phone to chat with a vacationing Thea (?) at the homecoming party Felicity hastily throws for her back-from-beyond friend even as she mourns her offed-by-Oliver fiancé Detective Billy.

Ah! This was all a ruse by our intrepid Miss Snow as she uses DNA lifted from the party to prove Laurel is in fact the Black Siren from Earth-2, last seen locked up at S.T.A.R. Labs on The Flash. Prometheus, the Michael Dorn sound-alike villainous archer, has used The CW app and the Arrow Cellar-like security defenses of S.T.A.R. Labs to set doppelganger Laurel loose on Team Arrow. Black Siren Laurel lays the smack down and jets, only to call Oliver on the phone later. Oliver, fresh from convincing District Attorney Adrian Chase to take on Diggle's case against the U.S. government, agrees to meet Laurel-2 in the hopes of bringing her over to the sides of the angels. Felicity – not in a trusting mood, to say the least – confronts a captured Laurel and gets her to reveal her duplicitous tugs at Oliver's heartstrings.

Laurel-2 escapes, Team Arrow tracks her to – wait for it – a warehouse where she and Prometheus take out the whole squad. Of course Oliver leg sweeps and backflips Promo to a draw before saving Felicity from a fatal Black Siren scream. Black Siren succumbs (this time for sure!) by a portable sonic dampener cobbled together by Curtis a/k/a Mister Terrific, embracing his mathletic abilities over his athletic inabilities.

Chase uses street smarts and a good chin to keep Diggle locked up in a S.T.A.R. City cell and out of clutches of the traitorous General Walker. Oliver gets beat from tip to quiver in Flashbackistan by the guy who betrayed the Bratva but is rescued by Talia Al Ghul in full gear as – give you two guesses – an archer!

THE GOOD –

Curtis had his secret vigilante life put on blast only for his husband Paul to leave him over it. Artemis betrayed him (and the team) and he got his butt kicked again. Maybe this time the lumps on his head will set his brain straight and he will sit all the way down and invent some of those terrific T-spheres, as seen in the comic books.

THE BAD –

Katie Cassidy was always the broken arrow in the quiver of actors on Arrow – in my opinion – so I wasn't thrilled to see her return. Earth-2? A S.T.A.R. Lab prison break? Is it Tuesday night again? Okay, I can get with the show getting its speed force on and leaning into the fantastical elements of the CW comic book universe and the darker shadings of Laurel-2 should give Ms. Cassidy some plum scenes in which to flex her thespian muscles…maybe not.  Another missed opportunity for a woman to shine outside the confines of the Arrow Dumpling Gang. Speaking of which…

THE UGLY –

The episode picks up immediately after the end of the mid-season finale, which means its hours (maybe) since Felicity learned of Detective Billy's death. So she spends the episode throwing a party for Laurel-2, tending to Oliver's bruised psyche, trading her usual lickety-spit quick quips with the camera and being Familiar Felicity we all know, love and are growing tired of with each successive season. The character is not allowed to mourn her loss, show any feelings whatsoever about Oliver's role in her loss because she has to 'be there' for him as he learns another season one lesson for the umpteenth time. Emily Beckett Richards, get your butt to another show. A short stint on Shameless could be just what your career is begging for.

THE VERDICT –

Episode 510 Who Are You? – I don't know, but you look tired. Score – D.