Nightfall — William Woodall

When 23-year-old Micah McGrath suddenly finds himself thrust into a dangerous and ugly future after a lab accident, his only choice is to try and make the best life for himself that he can. But when the secret police get wind of his research into time travel, he soon becomes a virtual prisoner, forced to continue his work on behalf of ruthless captors who wouldn't hesitate to eliminate him the moment he becomes inconvenient. After a desperate escape attempt fails, Mike is faced with the brutal choice of near-certain death, or of abandoning everything he loves forever.