First Steps: The Modern
The Modern Defence is an important opening that can be played by Black against absolutely any White opening system. It is an ambitious, counterattacking weapon, favoured by dynamic players. White is initially allowed to occupy the centre but Black plans to undermine this structure in the middlegame with well-timed blows from the pieces and pawns. If Black gets it right then the white centre can be dramatically swept away. However, when it goes wrong, Black can be overrun.
First Steps books are based around carefully selected instructive games which demonstrate exactly what both sides are trying to achieve. There is enough theory to enable the improving player to get to grips with the opening without feeling overwhelmed. If you want to take up a new opening, First Steps is the ideal place to start.