The so-called serial stowaway won’t be spending time behind bars for boarding a London-bound flight last year in Chicago without a ticket. A Cook County judge sentenced Marilyn Hartman to 18 months of probation after she pleaded guilty yesterday to a felony trespassing charge. She must continue her mental health treatment and isn’t allowed at either O’Hare or Midway Airports without a ticket. Hartman admitted to sneaking past security at O’Hare in January 2018, boarding a jet and flying to London’s Heathrow Airport.