While walking through a park Navy Lieutenant Paul Booth is shot in the head and killed instantly. At the scene the team discover his identity, some peculiar burns on his fingers and an old business card of McGee's in his wallet. McGee has no recollection of ever meeting Booth, but Ziva discovers that he worked for a company called the Telles Research Group, who undertake cutting edge research and development for the Department of Defense.
McGee goes through the last people Booth called, discovering them to be his boss at Telles, Vince Westfal, his wife Justine and – a name which gives McGee a shock – Penelope Langston. Langston is a rebellious, hippy academic who also happens to be McGee’s grandmother.
McGee pays his granny a visit and she explains Booth was an old student of hers who kept in touch. She is very disappointed to learn that he was working for Telles. Brought in for further questioning, she reveals that she was recruited by Telles' late founder Max Ellswood during the Vietnam war to work on a special project which she believed was going to protect soldiers in the field. When Penelope discovered that its true aim was to develop a weapon, she threatened to blow the whistle, but the end of the war led to the project being cancelled.
Abby works out that the burns on the victim's fingers come from repeated use of an old photocopier in his basement. She believes he must have copied several thousand pages, but what document would he be copying? What project was Telles commissioned to work on? How did McGee's card end up in Booth's wallet? And was Booth really a student of Penelope's?
A contract killer murders a Navy lieutenant commander.