second filter.
It's a gas, actually. It was created to help soldiers stay awake for days at a time, but it went sort of wonky in that truly Howard Stark way. It intensified anger, hallucinations, psychosis.
General John McGinnis stole this chemical compound and used it on Russian troops to attack the Germans at Finow. It was a massacre, Steve. People tore one another apart. Howard tore up his weapons contract after Finow.
But a group called Leviathan stole it; they weaponized it, and we just recently dealt with it in New York (a test run by a Black Widow named Dottie and her associate, Johann Fenhoff, in a theatre killed several and we were able to fend off an attack on the city itself).
The pod brought a canister. I have it secreted away.