grim determination

Translations
мрачная решимость
He faced the challenge with grim determination.
Он столкнулся с вызовом с мрачной решимостью.
Definitions
A resolute and unwavering commitment to achieve a goal, often in the face of adversity or difficult circumstances, characterized by a serious and unyielding attitude.
Words
grim

adjective
мрачная
determination

noun
решимость