By Natalie Abrams
November 28, 2017 at 09:00 AM EST
Katie Yu/The CW

Why did the Nazi villains of Earth-X invade Earth-1?

As revealed at the end of Night 1 of the four-way superhero crossover, Overgirl (Melissa Benoist) is suffering from radiation overload from flying too close to the sun, so they need Supergirl’s heart in order to fix her. EW’s exclusive first look at Night 2 reveals how they plan to do that.

Plus: With most of the heroes banished to a concentration camp on Earth-X, Iris (Candice Patton) and Felicity (Emily Bett Rickards) will be forced to step up to save the day.

The four-way crossover between The Flash, Arrow, Supergirl, and DC’s Legends of Tomorrow continues Tuesday at 8 p.m. ET on The CW.