Halve the plums and scoop out and discard the stones. Pop the plums into your blender. Peel and break in the banana.
Finely grate in the zest from the lime and squeeze in the juice. Pick the basil leaves off their stalks and add the leaves to the blender too. Tuck in the baby leaf spinach.
Pour in 250ml cold water and add a few ice cubes. Blitz till smooth and combined.