While on the Justice Leagues orbiting Watchtower, an alert of dual emergencies in Gotham City calls Batgirl and Supergirl into action. They step into the teleporter. In the same moment, something attacks and damages the Watchtowers tech. The two girls return to Earth... but as one combined Super Hero! As they try to undo the mashup mishap, the merged pair also need to stop Two-Faces double-trouble crime spree thats wreaking havoc on the city. Can the two friends work through the fusion confusion and fight as one? Find out in this action-packed, illustrated chapter book thats perfect for young DC Super Hero fans!