3rd Person Singular without "S"

[crazyaboutenglish]

Hi,

Can anyone please explain to me why I don't put the "s" on the verb "need" in the following sentence when "it" is 3rd person singular? Is it because it's negative? I'm confused!

It need not turn out that way.

Thanks.

 

[5jj]

NEED can be used as a modal verb, especially in negative and interrogative forms.