Complete story — includes the ending
A Russian eco-activist sneaks onto a diplomatic plane to the US, but when he arrives, it is discovered that he has smallpox. Elizabeth initially suspects the Russian government, but is convinced by former United Nations employee Kat Sandoval that the cause is most likely the thawing permafrost in Siberia. The US, Canada, Greenland, China, and Russia agree to a program of efforts to prevent permafrost thaw. One of Henry's team tells him that there is an investigation into multiple agents across different agencies being revealed, just like Nasifa. Henry suspects that the leaker must be someone in the president's cabinet. Elizabeth hires Kat as policy advisor. Worried by Jason's obsession with his girlfriend, Henry and Elizabeth attempt to caution him about sex.
Sources and content license
Source and revision history · Adapted from Wikipedia contributors, Madam Secretary season 4. HTML formatting and reference markers removed. · Content license