The Diplomat season 1 finale left viewers with uncertainty about who Merritt Grove is and what he wanted. Grove appeared halfway through the finale and only had brief on-screen appearances before an explosive closing scene. Grove was confirmed to be a former Member of Parliament in the United Kingdom, a detail that was told to Kate Wyler after she called the problematic Margaret Roylin asking for information on Grove’s background. Kate instructed Hal not to meet with Grove since he is an unofficial and unverified source of diplomatic intelligence, a boundary that Hal had crossed before.

https://screenrant.com/the-diplomat-merritt-grove-death-explosion-hal-wyler/