The Mechanic (1972 Film re: Assassination)

The Mechanic (1972 film)
https://en.wikipedia.org/wiki/The_Mechanic_(1972_film)
https://en.wikipedia.org/wiki/Charles_Bronson
https://en.wikipedia.org/wiki/Jan-Michael_Vincent
https://en.wikipedia.org/wiki/Jill_Ireland

A United Artists Film owned by MGM. Today it is owned by Amazon via SONY Pictures.

In Italy, Bishop and Steve approach a boat where their intended victim is supposed to be, but it becomes apparent that this was a trap and they are the real targets. Bishop and Steve are ambushed, but they manage to kill all their would-be assassins.

His apprenticeship apparently complete, Steve shares a celebratory bottle of wine with Bishop, having coated the latter's glass with brucine, a colorless and deadly alkaloid. When Bishop realizes that he has been poisoned, Steve taunts Bishop, saying "You said every man has his jelly spot. Yours was you just couldn't cut it alone." When Bishop asks Steve if it was because Bishop had killed Steve's father, Steve responds that he had not realized his father was murdered. Steve goes on to reveal that he was not acting on orders to kill Bishop.

Steve returns to Bishop's home to pick up the Ford Mustang he had left there. He finds a note affixed to the rear-view mirror, which reads: "Steve, if you read this it means I didn't make it back. It also means you've broken a filament controlling a 13-second delay trigger. End of game. Bang! You're dead." As Steve frantically reaches for the door handle, the car explodes, killing him.

https://en.wikipedia.org/wiki/Brucine