In the series
The meeting was set up by the Archive and Jared Kincaid as intermediaries of the dispute between Hendricks and Gard as the complaining parties against the Denarians who had abducted John Marcone. Harry Dresden had asked for the meeting on behalf of Marcone's people. Captain Anastasia Luccio came along as Dresden's second. Sergeant Murphy insisted on being present representing law enforcement. Michael Carpenter and Sanya, Knights of the Cross parked at a near distance for backup.
The Shedd Aquarium was chosen as neutral and public location. Only there was no public there because of the massive snow storm. Dresden and company had to trudge through knee-deep snow in order to enter through the employees entrance. All other entrances were closed off by huge snow drifts.
The Pentagram spell the Denarians used to capture Marcone was a test run for the spell they intend to use to contain and capture the Archive. It is set up to encompass the Oceanarium, an exhibit section of the Shedd Aquarium.
Dresden and company met Ivy and Kincaid there. Kincaid led Dresden to where Ivy was supposed to be waiting by the dolphin tank. Dresden knew where they would likely find her. Despite being the the Archive, Ivy's a kid and kids like cute, They found her by the Sea Otter habitat. Kincaid stopped Dresden from disturbing her moment of joy.
Nicodemus Archleone requested talking alone with Dresden before the meeting started. After blabbering awhile about nothing in particular, Dresden realized that the talk was a ruse and treachery was afoot. Dresden deduced that taking Marcone was just the means to the end and that the real prize was the Archive.