On Lian Yu, Lyla tells Team Arrow that The Monitor wants them to build a weapon to survive the Crisis.
Lyla tells Oliver that Lian Yu has seen a bunch of energy spikes lately.
Oliver tells William and Mia that he has accepted his death.
Diggle confronts Lyla. She says that The Monitor rescued her in Afghanistan. She made a deal with him to find heroes together to fight the Crisis in order to protect her family.
Just as Rene, Dinah, and Roy approach Lian Yu with plutonium for the weapon, a missle shoots down the plane they are in.
The team splits up to find Rene, Dinah, and Roy and to find the plutonium. William stays behind with Mia to build the weapon.
Diggle, Lyla, and Connor find Rene and Dinah. Rene is hurt.
Oliver find the plutonium. Edward Fyers and Billy Wintergreen appear and fight Oliver and Laurel. They disappear and Oliver finds Yao Fai.
Diggle, Dinah, and Connor find Roy injured. His arm is stuck under a piece of the plane. They have to cut his arm off to free him.
Oliver and Yao Fai fall into a trap.
Yao Fai uses the reflection of the sun to burn the ropes of the trap and sets them free.
Fyers and his men surround the camp just as Oliver returns. He plans to use the weapon that William built to defeat Fyers.
Team Arrow minus William, Lyla, and Roy fight Fyers and his men.
William figures out that Oliver's DNA is required to activate the weapon.
Oliver returns and picks up the device, but his DNA sequence doesn't match. Lyla's DNA does though.
Lyla activates the device and Fyers and his men disappear. A portal opens and Lyla goes through it.
A rescue boat from ARGUS is going to pick Team Arrow up from Lian Yu.
Oliver tells Diggle to make sure his kids return to 2040 and to tell Felicity to not separate William and Mia -- he wants them to grow up together.
The sky turns red and Lyla appears as Harbinger to tell Oliver and Mia that the Crisis has begun.
In Central City, Nash Wells is sucked into an energy hole. To be continued on Crisis on Infinite Earths.