A woman buys some pot at a pot shop. As she exchanges money for pot, we see the process of the money how it goes from customer to register to back room to armored truck. As the armored truck moves the money, it's robbed and stolen.
Riggs is smoking pot while watching TV when a commercial for Cialis comes on featuring lovey-dovey couples. Riggs is not amused and shoots the TV.
Trish is getting ready for work, when Murtaugh reminds her of their date night. She forgot about it, but will make arrangements. Murtaugh gets a call from Riggs.
Riggs is at the scene of the robbery when Murtaugh shows up. He thought they were meeting at the office and going together to the scene. There's banter between what is "here" and what is "there" before Murtaugh notices it was his old training officer that was driving the armored truck.
They discover the truck delivers for a company called Joint Assets that runs all the money for the pot dispensaries. Riggs and Murtaugh agree to meet there.
They talk with the woman in charge of the company and are given a file of her clients to investigate.
They arrive at a pot party looking to talk with someone and discover they need to talk with Lonnie and Donnie who owned the pot shop that the armored truck left from.
Lonnie and Donnie find Riggs and Murtaugh and while Murtaugh questions them, Riggs goes inside to check ID's of the pot smokers when he sees a girl who looks like Miranda. He follows her upstairs, but it's not Miranda and he stays in the room smoking until Murtaugh finds him.
Riggs is in Cahill's office telling her about his new case and gets a form that allows him not to be drug tested for three months. As he leaves he tells her about shooting the TV.
Murtaugh is talking to Ned when Riggs comes in. They discover that Lonnie and Donnie may be the prime suspects and head back to the pot party house where they find Lonnie and Donnie decapitated.
Murtaugh is at home talking with Trish when Riggs shows up. As Murtaugh goes upstairs to take a shower, Riggs makes himself at home in the kitchen making himself some fried bologna.
Murtaugh returns and Murtaugh shares how he and Trish met, then they talk about the case. They figure out drug cartels are somehow involved and visit with the Gang Unit to find out information. They borrow one of their guys named Cruz to help out.
They learn from Scorses that the beheading was done with a machete and Cruz gives information about a guy who is known for machetes and cattle prods.
They visit the auto shop where Paco works and end up in a fight and chasing him down, eventually catching him. They find out that the cartel doesn't know where the money is. That the only person who knew where the money was going was the driver, meaning Ned.
Murtaugh and Trish are on their date night when Ned calls claiming he has an emergency. When Murtaugh gets there he discovers Ned has the missing money and learns why. Riggs shows up and they decide to just take the money in and not take Ned in until the next day to give him a head start.
They leave with the truck when they get a call from Ned. The cartel has found him and wants their money back.
Riggs and Murtaugh meet the cartel on a bridge for an exchange of Ned for the money, but they are outnumbered. A gunfight ensues and it looks like Riggs and Murtaugh are done for when the cavalry shows up.
Ronnie wants Riggs to come for dinner and Riggs shows up outside, but has flashbacks and decides not to go.
Murtaugh and Trish have their date night outside on the car hood with burgers.