tip one's hand vs unmask

tip one's hand

verb
  • To inadvertently reveal any secret, particularly a secret that puts one at an advantage or disadvantage. 

  • In card playing, to accidentally reveal one's cards or hand. 

unmask

verb
  • To expose, or reveal the true character of someone. 

  • To cease engaging in masking, to cease disguising one's autism. 

  • To enable (an interrupt, etc.) by unsetting or setting the associated bit. 

  • To remove a mask from someone. 

  • To remove one's mask. 

How often have the words tip one's hand and unmask occurred in a corpus of books? (source: Google Ngram Viewer )