What: Gellert and Albus go Dark Lord hunting. It's the new in thing to do.
When: After
this exchange, wherein Albus agrees to help Gellert hunt down Riddle since Riddle agreed to cooperate with experiments if he gets caught.
Where: In the City.
Who: Gellert, Riddle, Albus.
Complete: Not yet.
Rating: PG, just for the sake of it.
Gellert turned his broom in a sharp circle, binoculars hanging around his neck. On their lenses, he'd smeared a version of the substance he made people inhale in order to have the magic in their body visible. That would allow him to spot magic being used.
It meant the City was a tight cluster of color and light, with swirls of magic hazing over the air so strongly that it was impossible to see anything specific there. Gellert wasn't sure if Riddle would think to hide in there, but from comments in Peter's journal and Riddle's own, he'd deduced that Riddle lived in a flat in the City and as he was inviting people there, probably still kept a presence there somehow.
Therefore, before anything else, Gellert was trying to find Riddle's flat. Being him, he'd chosen to grab a broom and float high in the air, near the peaks of the buildings, rather than trek along on foot. Kosa, however, had been assigned to walk through the streets and ask people if they knew where Tom Marvolo Riddle's dwelling was. She bore a quick sketch of him that Gellert had done based off what he'd seen at the party.
Albus was searching in his own way; the two of them had agreed that whomever found Riddle first would send a message via Patronus to the other, but not hesitate to engage He-Who-Must-Be-Hugged.