Don't, personally, see a lot of cargo jets heading from ORD to Halifax. Plus, rather unusual livery. Any particular story here - or not ?
Possibly a tech stop on their way to Europe. When I was a fueler at KYIP way back when, I fueled several Kalitta 747's heading for Gander (CYQX), then Ostend (EBOS), due to heavy cargo loads and a relatively short runway (7,500 ft) at KYIP. Coming out of O'Hare, seems like a tech stop would not be needed though. O'Hare has significantly longer runways... wonder what her final destination was...
As far as the markings, she had "SKY LEASE CARGO" titles on the other side. Not real sure why she's marked the way she is. She has different logos on either side of the tail too...