Who Is Sensor Girl

Plot

With its three founders (Cosmic Boy, Saturn Girl and Lightning Lad) having announced their intention to resign from active duty, the Legion of Super-Heroes holds its first major membership drive in years. Power Boy, Comet Queen, Mentalla, Energy Boy and Dev-Em are among the various candidates. Ultimately, five new members are voted in, including the telepathic/telekinetic Tellus, the extradimensional entity Quislet, Cosmic Boy’s younger brother Magnetic Kid, and Legion of Substitute Heroes co-founder Polar Boy, who finally accepts the Legion’s long-standing offer of membership. The fifth new member is Sensor Girl. She is a masked woman who keeps her powers and identity secret, but is voted in based upon a recommendation from Saturn Girl, who states that she “has the best of reasons to deserve Legion membership.”

Over the new few weeks, Sensor Girl displays a variety of powers. She is aware of an explosion occurring miles away before any of her teammates, illuminates the darkness with infra-red light, and displays impressive prowess in hand-to-hand combat. She properly analyzes the glandular imbalance in one of her teammates, and is able to see and hear through walls. Brainiac 5, grieving the death of his longtime love Supergirl, begins to suspect that Sensor Girl might actually be Supergirl — or a traitor in their midst. The mystery deepens when Brainiac 5 breaks into her quarters and discovers that she has been flying without using her Legion flight ring. Team leader Element Lad is reluctant to ask Sensor Girl to reveal her identity, as years earlier he was also admitted into the Legion on Saturn Girl’s recommendation alone. However, as teammates grow suspicious and internal conflict develops, he is forced to raise the subject with Sensor Girl. She responds by resigning from the team. As she leaves Legion Headquarters, Ultra Boy uses his penetra-vision to see through her mask, and is stunned when he discovers that her costume is empty.

Meanwhile, the Emerald Empress has reformed the Fatal Five, recruiting the Persuader (her former teammate), along with Legion reject Mentalla, and two additional criminals: Caress, a woman with an acidic touch, and Flare, a woman with destructive energy blasting powers and flight. The Legionnaires desperately search for Sensor Girl, worried that she might have accepted the Empress’ previous offer of alliance. Dawnstar tracks her to the cemetery planet Shanghalla, where the trail dissipates. Element Lad raises the subject of Sensor Girl’s qualifications with Saturn Girl. She reiterates that Sensor Girl deserves Legion membership, adding that "she was already a Legionnaire." On the planet Stratus, the new Fatal Five ambushes and attacks a small faction of Legionnaires (who were, ironically, searching for Mentalla), made up of Dream Girl, Colossal Boy, Tellus, and Polar Boy. Despite fighting valiantly, the four Legionnaires are overpowered and on the verge of losing. Sensor Girl arrives and leaps to the defense of her teammates, but she too is overcome by the Empress, who exposes the mystery woman’s true identity: Projectra.

Brainiac 5 finally deduces Sensor Girl’s identity, which is confirmed by Saturn Girl. Projectra had traveled to Shanghalla to visit the tomb of her late husband Karate Kid, who tutored her in hand-to-hand combat. She was able to fly without the aid of her new Legion flight ring by using the one she received when she originally joined the team years earlier. Her other seemingly endless abilities were the result of her illusion-casting powers, magically heightened by the spirits of her ancestors to include the ability to see through reality's illusions — including those of size, distance, time and death. Desiring to return to the Legion in secret, she and Saturn Girl developed the Sensor Girl identity.

Projectra (who re-adopts her Sensor Girl persona) and the other Legionnaires, having escaped from the Fatal Five, are forced to engage them in battle once again. As in the previous fight, the Legion members take a vicious beating from the Fatal Five, but do their best to fight on. However, they all soon realize that Mentalla is a mole in the Fatal Five, and has not truly betrayed the Legion. Using her powers, she possesses Flare and the Empress, using the former to destroy communication jamming satellites around the planet, and the latter to send out a distress call to the Legion via the Legionnaires' flight rings (the Empress had taken the flight rings from them at the beginning of the second battle to prevent them from escaping a second time). In retaliation, the Empress murders Mentalla. The psychic backlash from her death incapacitates Tellus, removing him from the battle. The two teams fight again, with the Legionnaires, now less one member, once again being brutally routed by the villains. One by one, the remaining Legionnaires are defeated. Only Sensor Girl is left. She is eventually able to single-handedly defeat both the Persuader and Flare before being overcome by the Empress and Caress. However, Wildfire and Dawnstar, having received the distress call, arrive, with Wildfire blasting and incapacitating the Emerald Eye, and Dawnstar defeating Caress. Sensor Girl, with her last bit of energy, punches out the Empress, thus ending the battle.

Afterward, Projectra abdicates the throne of Orando. The Legion officially votes her into the Legion again as Sensor Girl, accepting her role in the death of Nemesis Kid as a case of self-defense.

Post-Zero Hour

In post-Zero Hour continuity, a snake-like non-humanoid named Sensor joins the team, possessing illusion-casting powers similar to those in Projectra’s original incarnation.

Post-Infinite Crisis

In the aftermath of the Infinite Crisis miniseries, most of the Legion's original continuity has been restored. Elements of the Sensor Girl mystery are once again part of Legion history. Sensor Girl's supposed connection to Supergirl is removed, as the current incarnation of the Girl of Steel has not been killed.