Billy is slightly disconcerted by the message - new in town, and already recruited - but he didn't exactly make it a secret that he's a superhero when he arrived, either, and this is just the sort of potentially terrifying quest that heroes get recruited for. Granted, the Young Avengers tend to more or less stumble into things rather than get recruited, but there's something about this that satisfies his inner geek. And he's not about to turn down a mission that will not only help find a cure for the infected people he'd seen milling around the streets like oddly productive zombies when he looked out the window earlier, but also be able to send a message home - to let his friends know he's in some other dimension. That has a value he can't put into words, but it starts with not letting Magneto invade Latveria on the grounds of Doom having him captive and involves Teddy not maiming people out of worry (as hot as that is), so. Yeah, a valuable thing.

Figuring that the wards on the temple might mess with his magic, he flies to a nearby street and then heads inside on foot from there, all kitted up in his uniform and with his staff in hand. And then he's just... going to look around until he finds the people with the magic bottle.