A former professional assassin code-named Ladybug returns to work with a
newly positive attitude, where he is tasked by his handler, Maria
Beetle, to collect a briefcase aboard a bullet train travelling from
Tokyo to Kyoto after her normal contact, Carver, is forced to call out
due to illness. Unbeknownst to Ladybug, three other killers are on
board: hit-men brothers Tangerine and Lemon, and deceptively innocent
schoolgirl The Prince. Tangerine and Lemon have been hired by White
Death, head of the world's largest crime syndicate, who seized control
of the Japanese underworld years before.
Having recovered the
crime lord's kidnapped son and the briefcase containing his US$10
million ransom, the brothers are delivering both to Kyoto. The Prince
summons another assassin, Yuichi Kimura, to the train, having pushed his
young son off a building. With an associate at the hospital ready to
finish the boy off, the Prince forces Kimura to cooperate with her plan:
rigging the briefcase and Kimura's gun with explosives to kill White
Death. Stealing the briefcase, Ladybug is forced to kill another
assassin, The Wolf, who arrives seeking revenge for the deaths of his
wife and his entire cartel, poisoned at their wedding.
Realising
the briefcase is missing, the brothers find White Death's son dead by
poisoning. The Prince leads Tangerine to believe Ladybug is responsible,
while Ladybug attempts to negotiate with Lemon but is forced to subdue
him. Ladybug runs into the Wolf's intended target, The Hornet - the
poisoner who massacred his wedding, hired to kill White Death's son. She
stabs Ladybug with a syringe of boom-slang venom but he injects her as
well, then saves himself with her only dose of anti-venom, and she dies
instead.
Fighting Tangerine to a stalemate, Ladybug tries to help
him convince White Death's men that his son and the briefcase are safe,
then kicks Tangerine off the train. Suspicious of Kimura and the
Prince, Lemon shoots Kimura but succumbs to a bottle of water drugged by
Ladybug, and is shot by the Prince. Climbing back inside the train,
Tangerine finds his brother's body and confronts the Prince, but is
fatally shot in a scuffle with Ladybug. Kimura's father, The Elder,
boards the train and reveals himself as a former Yakuza lieutenant whose
wife and clan were killed in White Death's rise to power.
Ensuring
his grandson's safety by having the Prince's associate killed, he and
Ladybug find Kimura and Lemon still alive, and they all prepare for the
ambush awaiting them. The train arrives in Kyoto, and Ladybug is met by
White Death and his men. The Prince, revealed to be White Death's
disgruntled daughter, tries to goad him into firing Kimura's
booby-trapped gun, but he instead tells her she was never part of his
plan. The White Death reveals that he hired all the assassins aboard the
train as revenge for the murder of his wife.
After Tangerine and
Lemon massacred his men during a job in Bolivia, his wife was called to
bail their son out of jail and was killed by Carver, who meant to
assassinate her husband. And the surgeon who was going to save his wife
was poisoned by the Hornet, ensuring her death by killing the one person
who could've saved her. Blaming the brothers, Carver, the Hornet and
his own son, White Death arranged for all the assassins - including the
Wolf, and Ladybug, who unwittingly replaced Carver on the train - to
kill each other and his son. Before White Death can kill Ladybug, the
briefcase bomb is triggered, knocking them both onto the train which
Lemon sets back in motion.
As the train speeds out of control,
the Elder duels White Death while Kimura and Ladybug fight off his
henchmen. Lemon tackles a thug off the train into the river below, and
the train derails, crashing into a nearby town. Ladybug is held at
gunpoint by White Death. He attempts to shoot Ladybug, but is killed
himself when Kimura's gun explodes. Ladybug, Kimura, and his father are
confronted by the murderous Prince, who is run over by Lemon driving a
truck carrying tangerines. Maria arrives to rescue Ladybug, who has
fully embraced a positive outlook on life.