Holmes and Watson are at a diner so Watson can introduce this guy she knows. He's from the London School of Economics and works for the SEC, so Holmes's anti-banker stance should be a problem. When he arrives, we learn that his name is Adrian and Holmes won't shake his hand. As soon as Adrian sits down, Holmes fires a hypothetical at him about what if he calls him in the middle of the night? What if he's poisoned and needs to take a particular drug? Adrian says he should take it to save his life. Holmes leaves. Outside, he tells Watson that the guy was just spouting platitudes. And he recommended drugs! Oh my stars! Watson mostly brushes off these objections and vows that they'll find him a sponsor. Holmes looks unconvinced, in my opinion.
Gregson calls because he senses that the subplot's scene is over and it's time to return to the mystery. The police have learned that the pager was prepaid, but luckily, they have the number. The same phone called the pager three times just before the explosion. And the phone that called belongs to a man who just got out of jail for arson.
Okay, really quick. That's not how pager work. You don't call the pager. When you want to page someone, you call the pager service. Then you enter your phone number and the pager company radios the pager, which displays your number. There's a phone number associated with the pager, but it's not "the pager's phone number." If the pager had a phone number, it would be a phone. So this whole thing is kind of a mess, but we'll have to try to ignore it.
Sorry. Back to the show! We're in the interrogation room, where Bell is talking to the arsonist. The guy admits that he called a number three times, but he says he was calling Miracle Deli, which was one number off. Holmes checks, and Miracle Deli does have that phone number. Gregson agrees that the coincidence bugs him, but not enough to cut the guy loose. Gregson leaves for the bomb squad's briefing. Holmes tells Watson says that the guy's watch is nine minutes slow and his fly is down, so he isn't precise enough to be a bomb maker. Watson points out that Ted Kaczynski looked like a hobo, which Holmes appears to accept as a valid objection.