Nightlock

Nightlock berries in the 74th Hunger Games.

"Not these, Katniss. Never these. They're nightlock. You'll be dead before they reach your stomach."

—Mr. Everdeen to Katniss Everdeen, on the effects of nightlock

Nightlock is a wild plant with poisonous berries that Katniss Everdeen and Peeta Mellark used to win the 74th Hunger Games. Katniss first heard about this kind of plant from her father. The berries are infamous for the lethal poisonous juices that are inside. The nightlock juice functions similarly to hemlock and potassium cyanide, and is so toxic that it can kill anyone who eats it in a matter of seconds. Katniss' father cautioned that anyone who ate nightlock would be dead before the berries even reached his or her stomach. Although most likely an exaggeration, Foxface died very quickly after consuming them. The only known sources for these deadly berries are in the arena of the 74th Hunger Games and around District 12 and District 13. 

74th Hunger Games

Peeta and Katniss find Foxface's body after she ate the berries.

Foxface, a female District 5 tribute, died after consuming them during the Games when she stole them from Peeta. She believed they were edible and did not know they were lethal. Peeta himself had mistaken them for edible berries, possibly the blueberry-like berry, that Rue had shown Katniss when they had formed an alliance. Katniss stopped him from eating any, remembering her father's warning, "Not these, Katniss. Never these. They're nightlock. You'll be dead before they reach your stomach." She and Peeta kept some in a bag in case they could trick Cato into eating them. On the last morning of the Games, when Cato was dead, the rule allowing two victors was revoked. Katniss, instead of battling against Peeta, in response, pulled out the nightlock berries, giving some to Peeta and keeping a small handful to herself. In the film, they then held them out to clarify their intentions and on the count of three, placed the berries closer to their mouths. But in the book, Katniss and Peeta put them in their mouths. Before they could swallow them, Claudius Templesmith took back the change, and are then both announced as the victors of the 74th annual Hunger Games, so Katniss ran to the lake to wash any remaining nightlock juice from her mouth. This scene was not included in the 3-hour long recap after the Games as it was a sign of "rebellion".

Later uses

Near the end of the movie, Seneca Crane is locked in a room with a table in the center of the room with a bowl filled with nightlock berries. The shot ends before anything else happens, leaving Crane's demise ambiguous but able to be inferred, much like his fate in the book. It is thought to be a cruel twist likely ordered by President Snow for allowing both Katniss and Peeta to win.

Nightlock is also the keyword for the Holo and when said three times in a row causes the Holo to self-destruct, killing everyone nearby.

The purple poison pills from District 13, given to the soldiers in Mockingjay, were also named nightlock. They were known to have the same effect as the berries themselves.

Real plants similar to nightlock

Nightshade Berries

The name "nightlock" is derived from two real poisonous plants. Deadly Nightshade (Atropa Belladonna) and Hemlock (Conium Maculatum) are both extremely poisonous plants (though the Solanaceae family, which includes Deadly Nightshade also includes many edible plants such as tomatoes, potatoes, and chili peppers, and the Apiaceae family also includes carrots). Deadly nightshade berries are similar in appearance to nightlock. Both nightlock and the real hemlock are known for their immediate effects and are commonly mistaken for edible plants—nightlock for Rue's berries and hemlock for wild carrots. Seneca Crane's execution by nightlock berries is clearly reminiscent of Socrates' execution by hemlock after he was tried for "corrupting the youth" and "questioning the gods".

Nightlock is said to look like an edible type of berry Rue had found in the arena, which may be blueberries, since they fit the same description.

Trivia

• In the making of the first movie, the stylists were said to be annoyed with the berries, as they stained the actors' clothing.