The Spare Man by Mary Robinette Kowal

Tesla Crane, a brilliant inventor and an heiress, is on her honeymoon on an interplanetary space liner, cruising between the Moon and Mars. She’s traveling incognito and is reveling in her anonymity. Then someone is murdered and the festering chowderheads who run security have the audacity to arrest her spouse. Armed with banter, martinis and her small service dog, Tesla is determined to solve the crime so that the newlyweds can get back to canoodling—and keep the real killer from striking again.