|For the altered Framework version, see Rescue in Bahrain|
After being selected to join an Inhuman community, Russian citizen Eva Belyakov underwent Terrigenesis and developed enhanced strength. A subsequent encounter with a member of Russian intelligence, in which she survived being hit by a car and emerged unharmed, prompted S.H.I.E.L.D. to label her as an Index candidate.
Years later, Eva approached her former mentor Jiaying and tried to convince her to let her daughter Katya undergo the process. Jiaying, however, rejected the request after Katya began displaying signs of psychopathic schizophrenia.
Outraged, Eva stole several Terrigen Crystals and used them to put Katya through the transformation. Katya subsequently gained the ability to manipulate other people's senses to the point of complete physical and mental domination.
Desperate to supply Katya with fresh victims, Eva embarked on an international killing spree, all the while unaware of the fact that her actions were attracting S.H.I.E.L.D.'s attention.
- "A civilian girl and a few of our guys were stuck inside a building being held by the followers of this gifted individual. Or worshippers. We never found out."
"She took it upon herself to get them out. Said she could fix the problem. So she went in, crossed off the enemy force."
- ― Phil Coulson and Skye[src]
Upon taking notice of Eva's activities and tracking her down to Manama, Bahrain, S.H.I.E.L.D. dispatched a small team to analyze her for the Index. The team, led by agents Phil Coulson and Melinda May, did as they were told, unaware of Katya Belyakov's existence or her abilities.
An attempt to negotiate with Eva quickly failed and resulted in the entire team, minus Coulson and May, being held hostage along with Katya, who was blending in so she could continue to satiate her thirst for carnage.
The two remaining S.H.I.E.L.D. agents pursued Eva to a nearby warehouse, where May convinced Coulson to let her confront Eva alone as there was no time to call for backup. Infiltrating the warehouse with only her gun and a knife, May took down Eva and several Bahraini mercenaries under Katya's thrall.
It was then that an enraged Katya, who witnessed her mother's murder, revealed herself to May and asked the S.H.I.E.L.D. agent to take her hand so she could "feel her pain". She then killed the remaining mercenaries and prepared to do the same to the subjugated S.H.I.E.L.D. agents, forcing May to fatally shoot her.
Immediately following the incident, the entire S.H.I.E.L.D. team was brought out of the trance. Unable to remember what had transpired, Hart and O'Brien concluded that May had single-handedly killed all the mercenaries. The agents proceeded to give May the nickname "The Cavalry", a moniker she would grow to despise.
Traumatized by the incident, Melinda May became withdrawn from Andrew to the point where she divorced him. She later retired from field work and transferred to desk duty and administrative work.