Direct-only beelining movements moves the monster in the direction of the target but in case of an obstacle on its path the monster will just stop.
The monster will determine which of its eight adjoining squares is closest to the player and attempts to move there (i.e, it makes a beeline for the player). If the intended move was blocked, the monster does nothing.
The monster moves identically to creatures that move using brained normal beelining, unless the highest priority move is blocked by a brain-invisible object. Instead of attempting the second-best move as directed by a brain, the monster will stop moving.