Ahkos Laos, a former black-ops agent thought dead, attacks Barrett Fimmel in his home. NCIS confronts a woman holding a cardboard box outside its headquarters, who's considered a security threat. Rogers arrives to help. The box doesn't have a bomb inside. Instead, it's a severed hand. Attached to it is a quote from Dante's Inferno. The hand belongs to Fimmel, a former CIA operative.. The woman gives Callen two addresses by Fimmel. Both buildings are off the grid. Sam and Callen check the warehouse, while Deeks and Kenzi go to Fimmel's home. Sam finds a ringing cell phone held by another severed hand. The voice says "Tell Mother I'm coming home." Kenz and Deeks find Fimmel's upper half. Hetty is Mother. Hetty took in the abandoned Ahkos and trained him until the CIA took him away to become an assassin. The woman gives Rogers an address for Hetty only. Eric identifies the woman as Nathasa Ali. Ops gets knocked out. Nathasa was scarred in a U.S. drone attack which killed her whole family. Hetty is abducted. Deeks gets trapped in a room with a bomb. Sam tries to talk Deeks into defusing the bomb. Hetty's tracking pin is located in a lake but it's a decoy. Rogers tells Nathasa that Ahkos set up her family as targets. She tells them that Ahkos is taking Hetty to a natural-history museum. Kensi uses their car to pull the door off of the room Deeks is locked inside just before the explosion. He blames her for getting him into the assassin's life and for not protecting him. Callen takes out Ahkos's soldiers but is stopped by Ahkos. But Hetty stabs Ahkos then holds him as he dies. Nathasa gives Rogers a list of those involved in Ahkos's operations, with Hetty's name on it.