The Essex House for Mutant Rehabilitation was an orphanage owned by the Essex Corporation for lost or wayward mutant children.
The Essex House was a foster home specializing in housing and containing young mutants. Under the direction of their headmaster, mutants were physically and psychologically abused using religious indoctrination. Domino was raised at this facility and escaped when she was a teenager.
Russel Collins, aka Firefist was one of the mutants raised at the Essex House for Mutant Rehabilitation and was tortured and experimented on by the Headmaster on a daily basis. One day, Firefist had enough and lost control, attacking the people of the facility and destroying the area.
Deadpool and X-Men members Colossus and Negasonic Teenage Warhead responded to the incident and arrived at the scene in an attempt to detain Firefist. Firefist violently resisted, but eventually Deadpool was able to subdue him. However, when Firefist revealed to the mercenary what the staff members were doing to him, Deadpool killed some of them before Colossus detained both the mercenary and the pyrokinetic in the Ice Box.
Soon afterwards, Firefist escaped from the Ice Box with Juggernaut, and later returned to the Essex Home in order to kill the headmaster as revenge for what he did to the young mutant, but the X-Force and Cable were able to stop him, as Deadpool managed to talk Firefist out of it. The facility however was destroyed due to the battle between Colossus and Juggernaut, while the children still inside were freed by Domino.
Once freed Yukio and Negasonic said the freed children would be brought to the X-Mansion.