Faraday cage in danger?

Electricity and Magnetism Level 2

The above figure shows a Faraday cage that is an enclosure formed by a conductive material or a mesh of such material. If a Faraday cage which has a cubic shape with edge length $2 \text{ m}$ is placed in an electric field of $E = 400 \text{ V/m},$ what is the electric field in the cage?