prodreti

1. (of water, light, sound) to penetrate; to get in; to seep in
   Voda je prodrla u podrum tokom noći. — Water got into the basement during the night.
   Kroz zavese nije prodrla ni trunka svetla. — Not a ray of light got through the curtains.
2. (of troops, people) to break through; to push into
   Neprijateljska vojska je prodrla duboko u zemlju. — The enemy army pushed deep into the country.
   Demonstranti su prodrli u zgradu skupštine. — The protesters broke into the parliament building.
3. (figuratively) to penetrate; to get to the heart of
   Firma je prodrla na evropsko tržište. — The company broke into the European market.
   Teško je prodreti u suštinu ovog problema. — It's hard to get to the heart of this problem.

Usually used with u + acc. (prodreti u grad) or kroz + acc.; the imperfective is prodirati.