One of Topham's dark eyebrows, so in contrast to his silvery hair, slid up inquiringly, and he grinned at Drew's involuntary but emphatic nod.
Topham's hair had been brown before it turned silver.
mnli hypothesis: Topham's hair had been brown before it turned silver. premise: One of Topham's dark eyebrows, so in contrast to his silvery hair, slid up inquiringly, and he grinned at Drew's involuntary but emphatic nod.