When Sara arrives at Star City, She puts a cloaking device on the jump ship before landing. Then she lands the ship and gets out.
Before leaving the waverider, she called Nyssa and asked her to meet her at her old safehouse in Star City. If anyone used the Lazarus Pit to bring Laurel back from the dead, it would have been her or Oliver. She didn't know which one it was but she was going to find out who did it.
When Sara got to the safehouse, she found Nyssa waiting for her inside.
"Thanks for meeting me," Sara tells Nyssa.
"I would move heaven and Earth to see you again beloved." Nyssa reply.
"So would I, but this is business, not pleasure."
"I see and what business are you seeking?"
"Information."
"What kind of information?"
"Laurel came to see me today."
"Laurel is dead unless you... No, it couldn't be."
"What is it, Nyssa?"
"The woman that came to you today was Laurel's doppelganger, Black Siren."
"I should have known."
"It's not your fault but I can't believe no one told you about her."
"Who else knows about her besides You?"
"Your father, Oliver and his team, and team Flash."
"And now I know about her."
"Yes you do, but I must warn you not to take her on alone."
"How come?"
"Because she's a Metahuman."
"Great."
"What are you going to do?"
"I don't know."
"Maybe I should go with you."
"If I can't beat her by myself, what makes you think we both can take her?"
"Because two assassins are better than one."
After they took a shower together, Ava and Alex got dressed. Then Ava gives Alex a goodbye kiss and parted ways with Alex and went to work.