A passerby called 911 just after 4am after seeing a white Mercedes Benz upside-down in a ditch in the 24100 block of Clay Road near Peek.
Deputies arrived to find the man dead and his wife seriously hurt.
Investigators say the driver was going about three times the speed limit down the dark, rural roadway when he lost control. They crashed into a ditch and flipped several times, landing on the roof of the sedan.
The woman went to Memorial Hermann Hospital by Life Flight. At last check, she was in critical condition.