An old Oxford girlfriend of Mulder’s asks for his help on an international case concerning the unexplainable execution of several British dignitaries, and they encounter an assassin who can produce…

After Zoom unleashes an army of Earth-2 meta-humans on Central City, Barry is shaken when he sees their leader is the Black Canary’s Earth-2 doppelganger, the Black Siren. Meanwhile, Wally…

When Cisco gets a vibe of Eobard Thawne, Barry and the team don’t believe it. But, after an attack at Mercury Labs, Christina McGee confirms that the Reverse Flash is…

Barry and the team look for another Firestorm match for Dr. Stein. When the team meets Jefferson “Jax” Jackson, Caitlin has her reservations about whether Jax is the right match…

Felicity and Ray Palmer pay a visit to S.T.A.R. Labs for help getting Ray’s ATOM suit to work, and ask Cisco for help. Meanwhile, a young tech expert raises havoc…

Barry enjoys the annual tradition of tree trimming and gift exchange with Joe and Iris. He gives Iris a touching gift, but the moment is interrupted by Eddie’s arrival.