Simplify the following text for a Grade 10 native English-speaking person.
Original: Percy and his friends must look for Artemis before the winter solstice meeting of the Olympian council , when the goddess 's influence could change an important vote on the war with the Titans .
Simplified: Percy and his friends must look for Artemis before the winter solstice , when her influence on the Olympian Council could change an important vote on the war with the Titans .