The walk starts a couple of miles up Cader Road in the Ty Nant car park (which is pay and display).
Walk out of the car part and turn right along the quiet road. Turn left along the path just after the house "Ty Nant" on your left (by the phone box) and follow this path through the gate and and follow the stream on your left. Follow this path through a gate and right over the small stream ("Nant" in Welsh) and follow the path as it gets steeper up to the top of the ridge, passing a couple of gates on your ascent. Some parts of this path are eroded, but the path is in pretty good condition. When you get to the top of the ridge, turn RIGHT, ignoring the main path up the Cader which carries on to the left and also the one which carries on over the ridge and down the other side to "Llanfihangel-y-Pennant".
You are now on the ridge, so follow this feint grassy path with the wire fence on your right. This path can get a little boggy in wet weather, but the worst of it can usually be bypassed. Follow the path through the boulder field ("Carnedd Lwyd") until you reach a style near the summit "Craig-Las". Cross this and follow it to the next style on your right for a magnificent view over Cregennen Lakes, Barmouth, Cardigan Bay and the Llyn Peninsular.
You can either follow the feint grassy path up to the summit from here, or if you are not feeling so brave, go back to the first style and carry on along the path keeping the wire fence on your right. The fence is a good safety measure here as if the mist does roll in, as long as the fence is still to your right, you should be OK.
Now you on this lovely old meandering road which you will follow back the the car (for about five miles). Keep an eye out for old Milestones, sheep pens and ruined buildings, including a very impressive one called "Hafotty-Fach". All along this road you get the impressive view of Cader Idris to gaze up at.
If you want, you can take a detour to Cregennen Lakes, although they are probably worth a visit all of their own.