"in on it" meaning in Anglais

{
  "categories": [
    {
      "kind": "other",
      "name": "Locutions adjectivales en anglais",
      "parents": [],
      "source": "w"
    },
    {
      "kind": "other",
      "name": "Termes familiers en anglais",
      "parents": [],
      "source": "w"
    },
    {
      "kind": "other",
      "name": "Anglais",
      "orig": "anglais",
      "parents": [],
      "source": "w"
    }
  ],
  "lang": "Anglais",
  "lang_code": "en",
  "pos": "adj",
  "pos_title": "Locution adjectivale",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "Exemples en anglais",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Exemples en anglais à traduire",
          "parents": [],
          "source": "w"
        }
      ],
      "examples": [
        {
          "text": "He was in on it all along. I knew we shouldn't have trusted him."
        },
        {
          "text": "Do you think she's in on the plot?"
        }
      ],
      "glosses": [
        "Complice."
      ],
      "id": "fr-in_on_it-en-adj-WxJLWp2~"
    }
  ],
  "synonyms": [
    {
      "word": "complicit"
    }
  ],
  "tags": [
    "familiar"
  ],
  "word": "in on it"
}

{
  "categories": [
    "Locutions adjectivales en anglais",
    "Termes familiers en anglais",
    "anglais"
  ],
  "lang": "Anglais",
  "lang_code": "en",
  "pos": "adj",
  "pos_title": "Locution adjectivale",
  "senses": [
    {
      "categories": [
        "Exemples en anglais",
        "Exemples en anglais à traduire"
      ],
      "examples": [
        {
          "text": "He was in on it all along. I knew we shouldn't have trusted him."
        },
        {
          "text": "Do you think she's in on the plot?"
        }
      ],
      "glosses": [
        "Complice."
      ]
    }
  ],
  "synonyms": [
    {
      "word": "complicit"
    }
  ],
  "tags": [
    "familiar"
  ],
  "word": "in on it"
}