Plan B is a bag of weapons that makes several appearances throughout the seasons.
Before trying to rescue Michael Pope from being killed by a group of corrupt cops, Reese realized that he would need “more than a cell phone”. He declined Finch's, offer to supply him with legally purchased weapons as he feared they could be traced. Reese surprised Anton and his gang, shooting all of them but Anton, and took several guns and the bag from them. (“Pilot”)
Finch: “In other words, the idea of letting a 14-year-old hire you to avenge his brother has backfired?”
In “Flesh and Blood”, Reese hands the bag over to Carter so that she can protect herself against Elias trying to kill several Mafia dons. Fusco, whom Carter asked to be her backup, doesn't know where the bag and the guns came from and jokingly asks if she was about to ship back to Iraq.
In “The Contingency”, it is revealed that Carter was still in possession of the bag when she helped save Reese’s life by shooting Titus with a gas gun before he could strangle Reese. Carter returned the bag to Reese afterwards.
In “YHWH”, the bag is seen with Reese when he defends the electrical substation in Brooklyn from Samaritan's operatives while Finch and Root tries to extract the core heuristics of the Machine into the briefcase.
Among others, the following guns are stored in the bag:
- Heckler & Koch G36C – one of the guns lying on the table when Anton and his gang discussed their next deal. (“Pilot”)
- Heckler & Koch MP5K - compact variant of the ubiquitous MP5 sans stock and with integral vertical foregrip; is the weapon that Anton picks up while trying to act tough before his father calls him out on being an idiot. This particular one appears to be an MP5KN, having the polymer lower "Navy" style ambidextrous trigger group.
- Heckler & Koch MP5SD6 - another variant of the MP5, the SD is notable for not only the (extremely) large integral sound suppressor and shortened, ported barrel (to bleed pressure into the suppressor's cavities, negating the need for special subsonic ammunition as standard velocity 9x19mm rounds never become transsonic thus eliminating the "crack" of a projectile breaking the sound barrier), which together with the legendary H&K design and fabrication results in one of the quietest self-loading firearms made; firing the weapon at steel targets from just 20 feet using 147gr JHP+ 9x19mm rounds (fairly heavy with higher velocity than most), the sound of the weapon cycling (i.e. bolt cycle, extractor ejecting spent casing, forcing next round up ramps and into chamber, etc), a very fast "mechanical" sound, is the loudest sound the weapon itself makes (and something that is so many orders of magnitude quieter than a regular weapon discharge that it is imperceptible on nearly any other weapon), and the round impacting the steel down-range, the "clank" of metal on metal, is the loudest noise. Firing it with the selector on automatic, which empties a 30 round magazine in around 3 seconds, and it's quieter than two people talking at a distance of 5 feet.
- AR-15 Carbine (Unknown Make) - Seen with an "M4 Style" barrel, carbine-length gas system, and a drop-in front railed foregrip that retains the Delta Ring (rather than the much superior free-floated type, which mounts to the receiver and unlike the former, result in zero external pressure on the barrel); it is seen at the end of the table furthest from the door.
- M79 grenade launcher – Reese used that gun to shoot at Stills' car in “Pilot”.
- Remington 870 Police Magnum – the gun Reese uses to save Darren McGrady. (“Wolf and Cub”)
- Franchi SPAS-12 – visible in the bag when Carter prepares before taking in the dons. She also used the gun to shoot at Elias’ men at the Covenant Club. (“Flesh and Blood”)
- FN F2000 assault rifle – the gun Carter used to defend the safe house where she and Fusco kept the dons. (“Flesh and Blood”)
- DefTech 1315 37mm – the gun Carter used to save Reese from Titus. (“The Contingency”) Finch would use the same gun when he prepared to break Reese out of Rikers Island in “Prisoner's Dilemma”. Carter also uses it to hijack the truck full of drugs in “Endgame” by firing a smoke grenade through the windshield to force the drivers to leave the cab. When reviewing the security camera footage of the hijacking, Shaw notes that Carter can handle a "thirty-seven mill," and Reese realizes aloud that it's his grenade launcher (the scene is almost identical to Reese's impressive performance in “Pilot” when introducing Stills and HR to a compressed CS Gas Grenade, although he was using the M79 40mm launcher).
- Desert Tactical Arms Stealth Recon Scout – a rifle used by Carter to observe and threaten Alonzo Quinn while he is coordinating HR's response to the earlier truck hijacking. (“Endgame”).
- Flashbangs/CS Grenades (specifics unknown) - visible on the table next to the MP5K when Reese is loading up his bag with a few new toys, about half the table's contents; they can later be seen serving double-duty as a teething object for a 6-month old infant after Finch continues his "decline into deviant behavior" and kidnaps her in Season 1