The idea in one sentence
Black pins the knight that defends e4 and gives up the dark-squared bishop to damage White's pawns; White gets the bishop pair and space.
♔ White's plans
- Gain space with e5
- Use the bishop pair and the dark squares Black left weak
- Attack the kingside with Qg4
♚ Black's plans
- Pin the c3 knight with ...Bb4
- Strike the pawn chain at its base with ...c5
- Double White's c-pawns and play against them
Pawn structure. Locked centre (e5 against e6 and d5); White's doubled c-pawns against Black's weakened dark squares.
How to learn it
- Read the idea and the plans: every move below serves one of them.
- In the story, ask of each move: what does it do, what does it stop, what does it prepare, why not the other one?
- Drill your side. At the key moves you name the idea first, then play the move.
- Missed moves come back first next time, and in your journal.
The defining moves
- 1...e6 prepares ...d5, so that the pawn on d5 is defended.
- 2...d5 challenges e4 at once.
- 3...Bb4 pins the knight that defends e4.
- 4.e5 gains space and shuts out the knight's best square, f6.
- 4...c5 hits the base of White's pawn chain, d4.
- 5...Bxc3+ gives up the bishop to double White's c-pawns.
The line follows the moves masters play most (Lichess masters database), each checked by Stockfish 19 at depth 22; where the book move is not Stockfish's first choice, the story says so. Scores are in pawns from White's side: +0.30 is good for White, −0.30 for Black.