The story begins when bank robber Carl Quigley (Miguel Ferrer) escapes from jail. Soon after his prison break Quigley enters a warehouse and recovers $1,000,000 he had hidden there sometime before his arrest (it is unclear exactly how he illegally obtained the money). Quigley, with the help of assailants Juice (Tone Lōc) and bank president Edward Biderman (Michael Lerner), devises a money laundering scheme where Quigley will exchange the bills from his hidden "nest egg" (which have been watermarked by the FBI) for unmarked bills in Biderman's bank.
After Quigley visits Biderman in his bank office to discuss his plan (along with threatening Biderman's family if he does not comply with it), Quigley explains that Juice will be stopping by Biderman's office with a check to be cashed for $1,000,000 the next day at 1:00. After the meeting, Quigley runs over Preston Waters' (Brian Bonsall) bicycle while he was riding it in the bank's parking lot. Pressed for time as he sees a police car patrolling the area, Quigley gives the boy a signed blank check and tells him to give it to his parents so they can buy him a new bike. Instead, the boy writes himself a check for $1,000,000 by printing it on his computer. Preston goes to the bank the following day and is directed to Biderman's office by a teller (as the teller could not approve a check that size themselves). Thinking that Preston is Quigley's assistant, Juice, Biderman cashes Preston's check with money from a safe hidden behind a painting. As Preston is leaving the bank, the real Juice enters Biderman's office with another check for $1,000,000. Realizing that Biderman mistook Preston for Juice, the trio begins a frantic search for Preston. Meanwhile, Preston embarks on an extreme shopping spree over the course of 6 days, buying a castle-style house (by outbidding Quigley using the voicebox on his computer over the phone) along with many other expensive items (limousine service, go-kart track, water slide, etc.). He spends $999,675 of the original $1,000,000. Preston covers himself by saying he is making these purchases for a millionaire known only as "Macintosh" who lives in the castle house (named after Preston's Macintosh Performa 600).
The entire time, Preston was being investigated by FBI agent Shay Stanley (working undercover as a teller at Biderman's bank) for money laundering as the bills Preston was using to make his purchases were Quigley's watermarked stolen bills. At a birthday party Preston throws for Macintosh that forced Preston into debt (it was also Preston's birthday), he is forced into a showdown with Quigley, Juice, and Biderman. When the trio is confronted by the FBI at Preston's castle house, Quigley claims to be Macintosh. However, with the FBI knowing that Macintosh had been using the watermarked bills, they arrest Quigley (who is pretending to be Macintosh), Juice, and Biderman.