Exciting and thrilling long episode of the three Chicago franchises. There are gas-leak-related explosions beneath the streets which create havoc and fires that Chicago FD has to address. There are also injured who are treated by the doctors from Chicago MD. However, there seems to be something odd about the underlying causes of the disaster which need to be investigated by the CPD. In doing so both firefighters and police detectives have to fight for their lives and those of many innocent victims in the subway that passes through that street and who are caught in the havoc, while their teammates and superiors above on the ground need to find ways to bring about solutions and identify the culprits.